Faculty of Physics

Sukurta: 10 September 2013

9 Saulėtekio, LT-10222 Vilnius
Tel. 236 6001, fax 236 6003
E-mail:
http://www.ff.vu.lt

Dean – Prof. Habil. Dr. Vytautas Balevičius

STAFF

67 teachers (27 habilitated doctors and 35 doctors), 48 research fellows (4 habilitated doctors and 58 doctors), 64 doctoral students.

Astronomical Observatory
Department of General Physics and Spectroscopy
Department of Quantum Electronics and Laser Research Centre
Department of Solid State Electronics
Department of Semiconductor Physics
Department of Radiophysics
Department of Theoretical Physics

MAIN RESEARCH AREAS OF THE FACULTY

Solid state physics and technology
Spectrometric characterization of materials and electronic/molecular processes
Laser physics and technology
Structure, functions and mutations of biomolecules in model and live systems
Physics of atoms, molecules and condensed matter
New materials, nano-structures and surfaces: synthesis, characterization, technologies
Structure and evolution of galaxies, stars and interstellar matter

DOCTORAL DISSERTATIONS MAINTAINED IN 2012

T. Čeponis. Radiation technologies for optimization of Si devise parameters and techniques for control of radiation defects.
T. Gertus. Yb:KGW femtosecond laser material micromachining system and applications.
V. Jukna. Conical wave triggered transient spatio-temporal effects in Kerr media.
D. Kaškelytė. Application of fluorometric techniques for diagnostic of tissue pathologic changes.
P. Každailis. Leaky acoustic waves in acousto-optic and acoustoelectric interaction.
G. Manolis. Optical and electrical properties of highly excited 3C SiC crystals and heterostructures (2012 December).
S. Nargelas. Investigation of carrier dynamics in InN, InGaN and GaAsBi by optical pump-probe techniques.
M. Pranaitis. Study of carrier transport, trapping and optical nonlinearities in polymers promising for optoelectronic applications.
S. Rudys. Development of the methods of broadband dielectric spectroscopy by investigating (1-x)(Na1/2 Bi1/2)TiO3 - xLa(Mg1/2 Ti1/2)O3 and other materials.
A. Uleckas. Contactless spectroscopy of native and technological defects in Si, Ge and GaN structures.

CONFERENCES AND SEMINARS ORGANIZED IN 2012

8th national conference LASERS: Science and Technology
19th international congress on Sound and Vibration
Vilnius Workshop on Nonlinear Spectroscopy and Open Quantum Systems

ASTRONOMICAL OBSERVATORY

29 M. K. Čiurlionio, LT-03100, Vilnius
Tel. 239 8764, fax 239 8767
E-mail:

Head – Dr. Vladas Vansevičius

STAFF

Professor: Dr. V. Vansevičius (part-time).
Docents: Dr. J. Sūdžius, Dr. A. Bridžius (part-time), Dr. A. Kučinskas (part-time), Dr. D. Narbutis (part-time), Dr. R. Stonkutė (part-time), Dr. D. Semionov (part-time).
Senior research fellows: Dr. S. Bartašiūtė, Dr. J. Sperauskas.
Junior research fellows: V. Deveikis, S. Raudeliūnas.
Doctoral students: V. Dobrovolskas, A. Ivanauskas, T. Mineikis, P. de Meulenaer.

RESEARCH INTERESTS

Galaxies, structure and evolution
Stellar populations in the Galaxy
Star clusters
Binary stars
Stellar photospheres

RESEARCH PROJECTS CARRIED OUT IN 2012

Projects Supported by University Budget

Stellar Systems - Chemodynamical Evolution. Dr. V. Vansevičius. 2009–2013.

The main results of 2012 were achieved in the stellar population study of the M33 galaxy. The disk galaxy chemodynamical evolution model was developed and applied to study a star formation history of the M33 galaxy. A new technique for star cluster parameter determination was implemented and applied for a cluster study in the M31 and M33 galaxies (a paper is accepted for publication in the Astronomy and Astrophysics Journal).
A long-term radial velocity monitoring of the large sample of stars using the Coravel spectrometer of the Vilnius University Astronomical Observatory and 3D hydrodynamic simulations of stellar photospheres with the CO5BOLD code were continued.

Projects, Programmes, Issues Supported by the Research Council of Lithuania

Project: A comprehensive study of pulsations, binarity and chemistry of post-AGB stars. Dr. J. Sperauskas. 2012–2014.

MAIN PUBLICATIONS

Articles

S. Bartašiūtė, V. Deveikis, S. Raudeliūnas, J. Sperauskas. The lower main sequence of stars in the solar neighborhood: model predictions versus observation // Baltic astronomy / Vilniaus universiteto Teorinės fizikos ir astronomijos institutas. Vilnius : Vilniaus universiteto Teorinės fizikos ir astronomijos instituto leidykla. 2012, Vol. 21, no. 3, p. 387-396.

W. Chen, S. Hu, R. Errmann, C. Adam, S. Baar, A. Berndt, L. Bukowiecki, T. EisenbeiĪ², S. Fiedler, C. Ginski, C. Grafe, R. Guo, M. Hohle, H. Hsiao, R. Janulis, M. Kitze, H. Lin, C. Lin, G. Maciejewski, C. Marka, L. Marschall, M. Moualla, M. Mugrauer, R. Neuhauser, T. Pribulla, S. Raetz, T. Rolli, E. Schmidt, J. Schmidt, T. Schmidt, M. Seeliger, . Trepl., C. Briceno, R. Chini, E. Jensen, E. Nikogossian, A. Pandey, J. Sperauskas, H. Takahashi, F. Walter, Z. Wu, X. Zhou. A possible detection of occultation by a proto-planetary clump in GM Cephei // The Astrophysical Journal. Philadelphia : Institute of Physics Publishing. 2012, Vol. 751, no. 2, Art. no. 118.

V. Dobrovolskas, A. Kučinskas, S. Andrievsky, S. Korotin, T. Mishenina, P. Bonifacio, H. Ludwig, E. Caffau. Barium abundance in red giants of NGC 6752 - Non-local thermodynamic equilibrium and three-dimensional effects // Astronomy and Astrophysics. Paris : EDP Sciences. 2012, Vol. 540, Art. No A128.

H. Ludwig, A. Kučinskas. Three-dimensional hydrodynamical CO5BOLD model atmospheres of red giant stars. I. Atmospheric structure of a giant located near the RGB tip // Astronomy and Astrophysics. Paris : EDP Sciences. 2012, Vol. 547, Art. No A118.

DEPARTMENT OF GENERAL PHYSICS AND SPECTROSCOPY

9 Saulėtekio, LT-10222 Vilnius
Tel. 236 6040, fax 236 6003
E-mail:

Head - Prof. Habil. Dr. Vytautas Balevičius

STAFF

Professors: Habil. Dr. V. Balevičius, Habil. Dr. L.Kimtys (prof. emeritus), Dr. G. Dikčius, Dr. V. Šablinskas, Dr. V. Gulbinas (part-time), Dr. V. Remeikis (part-time).
Docents: Dr. V. Aleksa, Dr. A. Gruodis, Dr. A. Maršalka, Dr. F. Kuliešius, Dr. L. Juodis.
Lecturers: Dr. K. Aidas, Dr. J. Čeponkus, Dr. V. Urbonienė.
Doctoral students: N. Galikova; M. Pučetaitė.

RESEARCH INTERESTS

Spectroscopy of atoms, molecules and condensed matter
IR, UV, Raman, NMR investigation of organic compounds of the organized structure in the liquid, solid phases and nano-crystals
Phase transitions and critical phenomena
Molecular interactions, hydrogen bonding
Matrix isolation FTIR spectroscopy

RESEARCH PROJECTS CARRIED OUT IN 2012

Projects Supported by University Budget

Spectroscopy of Molecular Processes in Biological and Mesoscopic Systems. Prof. V. Balevicius, Prof. V. Sablinskas. 2010–2014.

The temperature and composition effects on the phase transitions, hydrogen bonding with H/D exchange, non-equilibrium phenomenon and relaxation in some of imidazolium-based room temperature ionic liquids (RTILs), namely – the 1-decyl-3-methyl-imidazolium bromide- and chloride ([C10mim][Br] and [C10mim][Cl]) in aqueous (H2O/D2O) solutions - have been studied applying FTIR, Raman, 1H, 13C, 35Cl and 81Br NMR spectroscopies.
The difference between lyotropic liquid crystalline (LC) ionogel phase and the solid one has been revealed, the motion of RTIL and water molecules in the late one was found to be dynamically segregated. This also causes very different H/D exchange rates via H-bonds between RTILs and D2O molecules. The observed anisotropic 13C NMR signal shape for the terminal –CH3 group points to the difference between LC ionogel and the lamellar phases, where usually decreasing order parameter moving along hydrocarbon chain from the polar head is observed. The supramolecular structures, similar to some higher micellar RTIL aggregates are expected.
35Cl and 81Br NMR spin-lattice relaxation times as well as viscosity coefficients have been measured for both neat RTILs. Based on measured 35Cl and 81Br spin-lattice relaxation time values, respectively, 206 and 23 ms, as well as both RTILs viscosity coefficients, which slightly differ, it was found that 35Cl effective quadrupolar coupling constant is one order lower than that for 81Br, i.e. 1.8 MHz and 16.0 MHz, respectively.
Infrared and Raman spectroscopy was applied for structural analysis of biological samples. Chemical structure of kidney stones removed from 100 urological patients was analyzed by using KBr pallet FTIR technique. Some statistics on chemical composition of the stones was performed. For multicomponent kidney stones distribution of chemical compounds was analyzed by means of infrared spectral microscopy. New method for correscting of specular infrared reflection spectra was developed. The infrared and Raman microscopy was applied for studies of urinary sediments. Infrared spectroscopy of intercellular liquid of biological tissue was applied for detection of tumour areas.
Collisional cooling was applied for forming of molecular self-associates of monocarboxylic acids and intermolecular complexes between carboxylic acids and water. The complexes were characterized using high stability. The structure of cyclic and open dimers of butyric acid was studied by means of matrix isolation infrared spectroscopy. Conformational diversity of monomeric butyric acid as well as the structure of open dimers of the acid was analyzed. The self-associates of water (dimers and trimers) molecules were studied by means of matrix isolation in parahydrogen infrared spectroscopy.
Various carbon allotropes were studied by means of infrared and Raman spectroscopy. It was found that Raman spectral D mode is sensitive to both: defects in carbon nanotube by itself and to functionalization of the nanotubes.

International Science Programs and Projects

The Faculty of Physics as a partner of STEPS TWO network, made reports for the working groups one Curricula after Bologna & Lifelong Learning and three Physics Teacher Education & European Dimension at group’s meetings in Patras (Greece), Prof. G. Dikčius.

Bilateral collaboration between Lithuania and France - “Gilibert” project Photodynamics Study of Molecules Isolated in Parahydrogen and Rare Gas Solids. Nr. TAP-10/2011/LSS-120000-268, Dr. J. Ceponkus. 2011–2012.

EU research project in the frame of Integrating Activity on Synchrotron and Free Electron Laser Science (IA-SFS) program: High Resolution FTIR Studies of Collisionally Cooled Complexes Between Formic/acetic Acids and Water. Prof. R. Nyholm (Swedish National Laboratory of Synchrotron Radiation, Lund), Prof. V. Šablinskas (Vilnius University). 2011–2012.

Research project funded from the European Community’s Social Foundation Synthesis and Characterization of New Materials for Semiconductor- and Nano-Technologies by Means of Continuous and Ultrafast Spectroscopic Methods (Grant Agreement No. VP1-3.1-ŠMM-08-K-01-004/KS-120000-1756, project leader – V. Šablinskas). 2012–2014.

MAIN PUBLICATIONS

Monographs, Studies

I. Doroshenko, G. Picevič, V. Šablinskas. Klasternaja struktura židkich spiritov : issledovanije metodami kolebatelnoj spektroskopii. Saarbrucken : LAP Lambert Academic Publishing. 2012. 279 p.

Parts of the Books

J. Tamulienė, R. Vaišnoras, G. Badenes, L. Balevičius. View on the Magnetic Properties of Nanoparticles Com (m=6,8,10,12,14) and Co6On (n=1-9). Smart nanoparticles technology / edt. by Abbass A. Hashim. Rijeka : InTech, 2012, p. 467-496.

Articles

K. Kairytė, Ž. Lukšienė, M. Pučetaitė, V. Šablinskas. Differentiation of bacterial strains by means of surface enhanced FT-Raman spectroscopy // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 3, p. 276-283.

G. Dikčius, L. Kimtys. Branduolinė sauga per incidentų analizę // Visuomenės sveikata. Vilnius : Higienos institutas. 2012, priedas 2, p. 26-30.

R. Jasinskas, A. Maršalka, J. Šulskus, M. Mačernis, V. Augulienė, M. Kazlauskas, E. Lunytė. Meteorologinių sąlygų modeliavimas naujos kartos HARMONIE modeliu, vertinant radioaktyvių medžiagų sklaidą avarijų metu // Visuomenės sveikata. Vilnius : Higienos institutas. 2012, priedas 2, p. 31-35.

S. Strazdaitė, R. Barisevičiūtė, J. Čeponkus, V. Šablinskas. Conformational isomerism of 1-butene secondary ozonide as studied by means of matrix isolation infrared absorption spectroscopy // Central European Journal of Chemistry. Warsaw : Versita, co-published with Springer-Verlag GmbH. 2012, Vol. 10, no. 5, p. 1647-1656.

G. Trinkūnas, O. Žerlauskienė, V. Urbonienė, J. Chmeliov, L. Valkūnas. Exciton band structure in bacterial peripheral light-harvesting complexes // The journal of physical chemistry B. Washington : American Chemical Society. 2012, vol. 116, iss. 1, p. 5192-5198.

V. Balevičius, K. Aidas, I. Svoboda, H. Fuess. Hydrogen bonding in pyridine N-‘oxide/acid systems: proton transfer and fine details revealed by FTIR, NMR, and X-‘ray diffraction // The journal of physical chemistry A. Washington : American Chemical Society. 2012, Vol. 116, iss. 34, p. 8753-8761.

P. Klaeboe, V. Aleksa, C. Nielsen, A. Horn, G. Guirgis, M. Johnston. Infrared and Raman spectra, conformations, ab initio calculations and spectral assignments of 1-fluoro-1-silacyclohexane // Journal of molecular structure. Amsterdam : Elsevier Science. 2012, Vol. 1015, p. 120-128.

G. Guirgis, C. Nielsen, A. Horn, V. Aleksa, P. Klaeboe. Infrared and Raman spectra, DFT-calculations and spectral assignments of silacyclohexane // Journal of molecular structure. Amsterdam : Elsevier Science. 2012, Vol. 1023, p. 189-196.

G. Steiner, L. Mackenroth, K. Geiger, A. Stelling, T. Pinzer, O. Uckermann, V. Šablinskas, G. Schackkert, E. Koch, M. Kirsch. Label-free differentiation of human pituitary adenomas by FT-IR spectroscopic imaging // Analytical and Bioanalytical Chemistry. Heidelberg : Springer. 2012, Vol. 403, p. 727-735.

G. Lozada, J. Čeponkus, M. Chevalier, W. Chin, J. Mestdagh, C. Crepin. Nuclear Spin Conversion to Probe the Methyl Rotation Effect on Hydrogen-Bond and Vibrational Dynamics // Angewandte chemie (International edition). Weinheim : Wiley-VCH Verlag GMBH. 2012, Vol. 51, iss. 28, p. 6947-6950.

G. Lozada, J. Čeponkus, M. Chevalier, W. Chin, J. Mestdagh, C. Crepin. Photochemistry of acetylacetone isolated in parahydrogen matrices upon 266 nm irradiation // Physical chemistry chemical physics. Cambridge : Royal Society of Chemistry. 2012, Vol. 14, iss. 10, p. 3450-3459.

S. Krotkus, K. Kazlauskas, A. Miasojedovas, A. Gruodis, A. Tomkevičienė, J. Gražulevičius, S. Juršėnas. Pyrenyl-Functionalized Fluorene and Carbazole Derivatives as Blue Light Emitters // The Journal of Physical Chemistry Part C: Nanomaterials, Interfaces and Hard Matter. Washington : American Chemical Society. 2012, vol. 116, no. 13, p. 7561-7572.

V. Aleksa, G. Guirgis, A. Horn, P. Klaeboe, R. Liberatore, C. Nielsen. Vibrational spectra, conformations, quantum chemical calculations and spectral assignments of 1-chloro-1-silacyclohexane // Vibrational spectroscopy. Amsterdam : Elsevier Science BV. 2012, vol. 61, p. 167-175.

J. Čeponkus, P. Uvdal, B. Nelander. Water Tetramer, Pentamer, and Hexamer in Inert Matrices // The journal of physical chemistry A. Washington : American Chemical Society. 2012, Vol. 116, iss. 20, p. 4842-4850.

G. Pitsevich, I. Doroshenko, V. Pogorelov, V. Šablinskas, V. Balevičius, E. Kozlovskaja. Nonempiric Anharmonic Computations of IR Spectra of Ethanol Conformers in B3LYP/ńń-pVQZ Approximation (Stretch Ń-Ķ Vibrations) // American Journal of Chemistry. Rosemead : Scientific & Academic Publishing Co. 2012, Vol. 2, no. 4, p. 218-227.

COOPERATION

Institute of Physics, National Centre of Physical and Technological Sciences (Lithuania)
Technical Universities of Darmstadt and Dresden (Germany)
Paris Sud 11 University (France)
Institute of Bioorganic Chemistry of Polish Academy of Sciences, Poznan (Poland)
National Institute of Chemistry (Slovenia)
Copenhagen University (Denmark)
Lund University (Sweden)
Kiev University (Ukraine)
Belarus State University (Republic of Belarus)

OTHER SCIENTIFIC ACTIVITIES

Prof. V. Balevičius –

member of the international advisory board Horizons in Hydrogen Bond Research;
member of the international advisory board Nuclear Magnetic Resonance in Condensed Matter;
member of the advisory committee International School-Seminar of Galyna Puchkovska on Spectroscopy of Molecules and Crystals.

Prof. G. Dikčius –

national coordinator for the EMSPS scheme (mobility of students of physics);
ERASMUS coordinator for physics;
member of EUPEN network.

DEPARTMENT OF QUANTUM ELECTRONICS AND LASER RESEARCH CENTRE

9 Saulėtekio, LT-10222 Vilnius
Tel. 236 6050, fax. 236 6006
e-mail:

Head - Prof. Habil. Dr. Algis Piskarskas (until 31 August, 2012)
Prof. Habil. Dr. Valdas Sirutkaitis (since 01September, 2012)

STAFF

Professors: Habil. Dr. A. Piskarskas, Habil. Dr. R. Rotomskis, Habil. Dr. A. Stabinis, Habil. Dr. V.Sirutkaitis, Habil. Dr. V.Smilgevičius, Dr. R. Gadonas, (HP) Dr. G. Streckytė, Dr. A.Dubietis, Dr. G. Valiulis, Dr. A. Varanavičius, Habil. Dr. B. Kaulakys (part-time).
Docents: Dr. S. Bagdonas, Dr. A. Matijošius, Dr. O. Balachninaitė, Dr. V. Karenauskaitė, Dr. M. Vengris, Dr. V. Jarutis, Dr. A. Melninkaitis, Dr. V. Pyragaitė, Dr. V. Kudriašov, A. Čiuplys (part-time).
Lecturers: J. Jurkienė, Dr. R. Butkus, Dr. G. Tamošauskas, Dr. D. Paipulas, Dr. R. Piskarskas.
Senior research fellows: Dr. E. Gaižauskas, Dr. R. Grigonis, Dr. V. Vaičaitis.
Research fellows:, Dr. R. Antipenkov, Dr. M. Malinauskas, Dr. D. Kaškelytė, A. Čiburys, Dr. M. Peckus,
Doctoral students:, L. Damalakienė, V. Jukna, A. Zaukevičius, J. Adamonis, T. Gertus, J. Darginavičius, V. Kulvietis, A. Savickas, J. Galinis, A. Baškevičius, T. Kudrius, D. Kezys, V. Purlys, D. Majus, E. Gabrytė, V. Voiciuk, T. Stanislauskas, A. Žukauskas, G. Batavičiūtė, A. Alesenkov, P. Danilevičius, M. Matulionytė, L. Mažulė, S. Rėkštytė, K. Redeckas, K. Stankevičiūtė, K. Steponkevičius.

RESEARCH INTERESTS

Light energy relaxation in dye molecules, aggregates and biologically active molecules
Primary photophysical and photochemical processes and photostability of sensitizers
Photochemotherapy of cancer; fluorescence and absorption spectrometry of sensitizers used in photosensitized tumour therapy in vivo and in vitro
Imaging and spectroscopy of biologic objects
Nonlinear optics of Bessel beams
Investigation of linear and nonlinear properties of optical vortices
Investigation of optical parametric oscillation in periodically poled crystals
X waves in linear and nonlinear media
Self-guiding, supercontinuum generation and damage in bulk materials and coatings induced by femtosecond pulses
Optics characterization including reflection/transmission, scattering as well as absorption and laser-induced optical damage threshold in wide spectral range
Peculiarities of ultrafast exciton dynamics at reduced dimension in self-assembled molecular nanostructures and quantum dots
Laser submicro- and nanoscale engineering of functional 3d devices
Nonlinear scanning microscopy with tunable pico - and femtosecond lasers
Compact laser supercontinuum sources and applications
Nonlinear optical processes in gases and metal vapours
Photonic crystal resonators
High intensity ultrashort pulse generation by opcpa systems

RESEARCH PROJECTS CARRIED OUT IN 2012

Projects Supported by University Budget

Fundamental Processes in Optical nonlinear and Laser Systems. Prof. A. Piskarskas. 2009–2012.

The study is aimed at delivering a new approach in generation and amplification of few-cycle high-peak-power light pulses by means of optical parametric amplification (OPA). The proposed method combines the major features of OPA and chirped-pulse amplification (CPA), namely, the ultra-broad parametric bandwidth, which is achieved by achromatic phase matching, and amplification of stretched seed pulse, which is implemented by performing the far field amplification of the pulsed conical wave (PCW). Moreover, these features are brought in a simple setup, in which a pulse compressor is dismissed. We succeeded in numerical demonstration that the Gaussian wave-packet can be reshaped into pulsed conical wave just by means of lens and nonlinear crystal. We pointed out that performing the far field amplification of the PCW is the key for generation of localized PCWs with ultrahigh intensities. It allows to form ultra-intense and propagation invariant wave-packets capable to propagate over many Rayleigh range in the desired material. The proposed method allows achieving large energy gain factors, and renders the main features of the OPCPA technique, but does not require a pulse compressor stage. Thus, it might be considered as a key solution in OPCPA setups where the pulse compressor is a bottleneck. This method is suitable for parametric amplification of PCWs by means of four-wave-mixing in materials with Kerr nonlinearity. A relatively large energy gain factor can be achieved with the pump intensity below filamentation threshold.
The influence of the idler wave linear absorption to the parametric amplification process was studied. It was demonstrated that in the case, when idler wave absorption is large and nearly independent on frequency, the gain during parametric amplification becomes also independent on frequency i.e. the gain bandwidth becomes broader (or even unlimited). So, in the case of large idler wave absorption parametric amplifier sustains exponential gain with broaden amplification bandwidth. This implies that despite large losses pulse spectral components could be amplified till the same level as in lossless medium, but within broader spectral range, and consequently, should have larger energy. In such a way the idler wave absorption can increase OPA conversion efficiency.
A method for visible-to-infrared frequency conversion of unchirped sub-30 fs pulses by collinear difference-frequency generation and subsequent optical parametric amplification, which uses a commercial laser system consisting of an amplified Ti:sapphire laser and second-harmonic pumped noncollinear optical parametric amplifier, is proposed. As an experimental proof, generation of broadly tunable few optical-cycle pulses using BBO crystals in the wavelength range of 1.2–2.4 μm is demonstrated. After two-stage optical parametric amplification, we obtained sub-100 μJ pulses with 10 % pump-to-infrared conversion efficiency. The validity of the concept is supported by the results of the numerical simulations that also suggest the possibility of tuning range extension further in the mid-IR using the nonlinear crystals with better IR transparency (e.g., LiIO3, LiNbO3). Numerical simulations suggest that thanks to group velocity matching at 3.5 μm in LiNbO3 and at 4.2 μm in LiIO3 crystals, pulses with duration shorter than 2 optical-cycles at these particular wavelengths could be obtained. The proposed method could readily serve for design of compact ultrashort-pulsed IR sources for diverse applications. In particular, pulse energy and tuning range achieved by the developed source would ideally suit for fundamental and applied studies of femtosecond filamentation and related phenomena in solid state dielectric media under conditions of high order nonlinear absorption and anomalous group velocity dispersion, i.e., in the regime, which is poorly explored up to date.
By using the conventional axicon and the hologram combination, the spiraling zero-order Bessel like beam was experimentally generated and analyzed for the first time (to our knowledge). Non linear light beam propagation with this spiral beam was also demonstrated. The single shot method of the spiral beam creation is presented. The created structure is continuous in all x, y and z coordinates. It was found that the beam displacement is directly proportional to the depth of phase modulation. The period P that determines the distance over which spiraling zero order Bessel beam makes one revolution grows with growing period of phase spiral shape hologram. Obtained results are in a good agreement with the theoretical predictions. An axicon with a spiral phase hologram created on its slope or on a base is suitable for high energy spiral beam generation.
It was shown that at certain energy of Gaussian and Bessel beams the two-photon absorption starts, which is indicated by the two-photon fluorescence of tetraphyrol TPPS4 and biological dye Rhodamin C. The fluorescence intensity is very different for Gaussian and Bessel beams at the same pulse energy in Rhodamin C experiments. The fluorescence intensity depended on various parameters, such as the amount of the media, photosensitizer concentration and optical path of scattering media in TPPS4 experiments. In conclusion, the two-photon fluorescence can be excited by Bessel beam which pass through the scattering media and self-reconstruct. Rhodamin C in a scattering media the two-photon fluorescence (2PF) excitation by the mild focused Gaussian beam (F=~40 cm) along the cuvette (i.e. pump by light filament) is preeminent over the Bessel beam pump due to requirement of 10 times lower pulse energy, twice longer 2PF excitation distance in a scattering media and missing the very precise optical element like an axicon.
The investigation of the second harmonic (SH) generation from an incoherent wave was performed. The dynamics of pulse transformation and free-carrier generation associated with the nonlinear propagation of 1030 nm and 300 fs light pulses in Gallium nitride film has been studied by using pulsed digital holography with 25 fs temporal resolution. Domination of the Kerr effect at the leading part and electron plasma at the trailing part of the pulse has been identified from the reconstructed spatiotemporal phase-contrast images. Experimental results have been supported by the simplified numerical model capable to reproduce the main features of a dynamic process. We studied evolution of femtosecond laser ablation by employing novel method of time-resolved off-axis digital holographic microscopy. Phase and amplitude profiles of early shock front and ablation plume dynamics of irradiated tempered steel were reconstructed from the digital holograms. In order to gain additional information, digital holographic microscopy was combined with plasma emission imaging. By using both techniques simultaneously we studied material response to multi-pulse irradiation, shock wave propagation, ablation plume formation and plasma emission. The significant changes in ablation performance were observed when using multi-pulse irradiation if compared to widely investigated single-shot regime.
Influence of transverse and longitudinal phase matching on the spectral and intensity properties of third harmonic generation induced by the Bessel pump beams have been investigated both theoretically and experimentally. Transverse phase matching, revealing itself as a ring pattern in the third harmonic intensity angular spectrum was demonstrated in both the normally and anomalously dispersive media. The conditions were found for the optimization of this conical third harmonic signal.
Light-matter interaction processes relevant to femtosecond laser microfabrication by direct laser writing, as well as subsequent supercontinuum generation in transparent materials (the case of glasses, specifically) were studied theoretically. Developments in the numerics, modelling and analysis of the laser induced modification dynamics during filamentation from femtosecond light pulses disclosed that residual refractive index changes evolve both in forward and backward directions, forming prolonged tracks of modified index profiles (waveguides) in fused silica during repetitious laser shots. Additionally, formation of the waveguides causes fractioning of the light filament along the propagation axis at high pump intensity.
Induced during femtosecond filamentation waveguides were found to have significant impact upon the dynamics of higher order soliton and as such supectontinuum generation in glasses. Influence of the delayed Raman response function on the supercontinuum generation was studied in detail. Contrary to expectations, generated dispersive wave energy was found to have maximum value at the specific point, rather than continuously decreasing function. Furthermore, Raman affected maxima of the soliton self-acceleration velocity appears at the same values (of the delayed Raman response function parameters), where efficiency of the dispersive wave generation reaches its maxima.

Dynamics of Optical Excitation and Relaxation in Aggregated Organic and Biological Pigments. Prof. A. Piskarskas 2009–2012.

The influence of polymer 1D grating to optical properties of pseudoisocyanine iodide (PIC-I) J-aggregates was investigated. For this purpose different period 1D rectangular type gratings were formed out of polymers by using direct laser writing techniques. Then aqueous/ethanol solution with PIC-I and PVA were dropped on spinning substrate with polymeric structure. Transient absorption spectra of hybrid structures were measured. The exciton coupling to waveguide modes was studied also in thin films with J-aggregates. We evaporated 10-20 nm silver layer onto glass coverslip. Then hot PIC-I and PVA aqueous/ethanol solution was spin coated on silver. For registration of leaky emission Kretschmann configuration was used with index-matching oil between the sample and prism. Sample was optically pumped by mW 532 nm CW DPSS laser. An additional emission band at the long wavelength side in the fluorescence spectrum was observed. The position of this band depends on observation angle. Studies of temporal dynamics of molecular excitation in thin films have been performed by ultrafast transient absorption spectroscopy methods. The pump pulses were tuned to resonant and off-resonant wavelength. In the measured kinetics and spectra exciton lifetime of few tens picoseconds was observed at resonant pump. At off-resonant pump the strong and fast response of few hundreds of femtoseconds was observed in addition to the weak exciton relaxation component of few tens of picoseconds.
Some investigations are devoted to assessment of autofluorescence spectral signature differences of initial structural changes in the artery inner wall surface due to atherosclerotic plaque formation. We used the human artery samples (realistic system) with intension to identify particular spectral shape signatures of various level of disease injury with specifically designed fluorescence scanning system for remote screening of sample surface and 4D data collection (x, y coordinates, fluorescence intensity and emission wavelength). We are able to identify the spectral regions for injury assessment ant the assessment of structural tissue composition is undergoing morphological and spectroscopic data comparison.
A single point measurement spectrofluorometric method for high grade glioma resection extension control during the surgery in clinic was practically implemented. A portable single excitation-detection channel fibre-optic system is designed and first collected human glioma fluorescence spectra guiding tumour resection extension were achieved. The constructed fluorescence excitation/emission collection unit was specifically designed to explore single fibre probe for selective porphyrin excitation and emission collection in brain tissue. The excitation and collection realized through the same optical fibre (600 μm in diameter, length 2 m) the tip of which was kept distantly during the measurements. We used GaN diode laser operating in cw regime at the wavelength 405 nm with output power up to 16 mW. A spectrometer was used to register the fluorescence spectra detected at the tested doubtful brain tissue site during the surgery. The fluorescence signal coupling time during each spectrum recording was 50 ms. During the surgery a laser light at 405 nm was delivered to the tissue through a hand-held optical fibre. We used larger diameter fibre on purpose to have the possibility to overlook the tumour fluorescence prospect by keeping the fibre further from the tissue surface. Thus for the spectrum measurement the fibre was aimed closer at the doubtful tissue site.
PpIX in human glioblastoma tumour assigned with peaks at 636 nm and 706 nm was detected and allowed to distinguish marginal tumour during the surgery in reference to fluorescence spectral shape profiles. The spectral signatures measured at tumour, normal tissue site and marginal tumour. The surgeon performed tumour resection guided by spectroscopy results until no PpIX signal remained. The marginal tumour showed spectral differences in 450 – 600 nm spectral range which means that tumour cells are infiltrating and surrounded by normal brain tissue. In conclusion, we were able to effectively detect 5-ALA induced PpIX fluorescence in the human glioblastoma during surgical resection. The designed portable fibre-optic system for fluorescence measurements could provide the real-time intraoperative targeting of fluorescent tissue sites in the brain. Our first results obtained are promising and this system is undoubtfully very useful adjuvant technique for remote screening of brain tissues peculiarities and glioma removal control for clinical use in neurosurgery.
The sensitization of the inflamed knee tissues with endogenous porphyrins was studied qualitatively and quantitatively by means of the fluorescence spectroscopy in the experimental model of rabbit rheumatoid monoarthritis after injections of exogenous 5-aminolevulinic acid (ALA) or ALA methyl ester (ALA-Me). Spectroscopic assessment of endogenous porphyrins in rabbit rheumatoid arthritis tissues in vivo and ex vivo implied that the injection of ALA due to the higher PpIX fluorescence intensity on the skin surface is more appropriate for the diagnostics of inflammation, while ALA-Me due to the higher and more selective accumulation of PpIX in the inflamed synovium is more appropriate for the therapeutic applications.
The steady state and time-resolved fluorescence spectroscopy experiments were performed ex vivo on the human heart tissue specimens from hearth conductive system (HCS), myocardium (MC), and connective tissue (CT). Spectral analysis of results revealed that at least three fluorophores are responsible for the emission in the region of 430-550 nm. According to the lifetimes, the fluorescing constituents in all tissues should be the same. The fractional components of fluorescence intensity revealed a similar composition of MC and HCS; however, quantitative differences were observed between HCS and CT.
Absorption and steady state spectroscopic measurements on CdSe/ZnS quantum dots (QDs) coated with thioglycolic acid (TGA) and mercaptosuccinie acid (MPA) in biological model system were performed. Stability, photostability and spectral properties of quantum dots were investigated in aqueous media to reveal the effects of QDs interaction with bovine serum albumin (BSA). It seems that protein interaction with CdSe/ZnS-TGA quantum dots increases a photoluminescence quantum yield and makes them more stable. However, protein decreases photoluminescence intensity and quantum yield of CdSe / ZnS -MPA after its addition. These effects could be resulted by changes in the structure and stability of a QDs coating. It was shown that both light and biological media (proteins) are independent factors affecting QDs photoluminescence properties. The intensity and quantum yield of QDs photoluminescence in model media depends on method of QDs surface modification.
The fabrication of three-dimensional microoptical elements by the direct femtosecond laser writing of a germanium–silicon photosensitive hybrid material was performed. Germanium glass composites are very interesting for optical applications as they are photosensitive, and maintain high optical transparency in the visible and near-infrared bands of the spectrum. Here, we have used a germanium containing hybrid material to make nanophotonic structures and microoptical elements such as photonic crystal templates, prisms and spatial polarization plates, both on flat surfaces and fibre tips. Our results show that this germanium silicate composite is an excellent material for microoptics fabrication.
We applied femtosecond laser direct writing in photopolymers for manufacturing of conical microlenses and closely packed arrays thereof. We demonstrated the fabrication of high optical quality axicons of 15 μm in radius, having 150°, 160°, and 170° cone angles. Their optical properties and performance were modelled using the finite-difference time-domain method and compared with experimentally measured data. Additionally, optimization of the laser direct writing parameters regarding these types of micro-objects was performed. Closely packed arrays of axicon microlenses have potential attractivity in the fields of modern microscopy, light-based material processing, particle manipulation in microfluidic, and optofluidic applications.
Micro/nanostructuring of novel metal isopropoxides-silica containing hybrid sol-gel materials by the femtosecond laser direct writing technique was performed and applied for the fabrication of various microoptical/nanophotonic components. This approach enables one to photo-structure true three-dimensional objects with controlled sub-100 nm spatial definition. Due to self-smoothing effects surface roughness can be formed below 30 nm making this technique widely applicable for microoptical/nanophotonics devices in visible and near infrared wavelengths. After photopolymerization these materials inherit desired optical properties: high transmittance in 400 - 1500 nm spectral range and nearly glass matching optical refractive index. Doping with organic dyes or quantum dots offers additional functionalities. Fields of applications covers: light guiding, coupling/extraction, trapping, signal processing and transferring, microscopy, biology and etc. In brief, we investigated direct laser writing structurability of these materials and its optimization for manufacturing of microoptical/nanophotonic components. We successfully produced microoptical components such as aspheric and Fresnel lenses. We demonstrate the flexibility and reproducibility of this approach to fabricate custom shaped elements on the tip of the optical fiber, thus producing integrated microoptical devices. The micro/nanostructures were characterized by optical and scanning electron microscopies, and optical profilometry. Their optical functions were measured using custom built setup to serve the purpose. The obtained values were in close coincidence to the theoretical values. Further research in the direction of production integrated and multi-functional components to be applied in the fields of photonics, plasmonics and telecommunications as well as optofluidics are currently carried out.
The direct laser writing of polymeric materials for tissue engineering applications also was investigated. A femtosecond Yb:KGW laser (300 fs, 200 kHz, 515 nm) was used as a light source for non-linear lithography. Fabrication was implemented in various photosensitive polymeric materials, such as: hybrid organic-inorganic sol-gel based on silicon-zirconium oxides, commercial ORMOCER® class photoresins. These materials were structured via multi-photon polymerization technique with submicron resolution. Porous three-dimensional scaffolds for artificial tissue engineering were fabricated with constructed system and were up to several millimetres in overall size with 10 to 100 μm internal pores. Biocompatibility of the used materials was tested in primary rabbit muscle-derived stem cell culture in vitro and using laboratory rats in vivo. This interdisciplinary study suggests that proposed technique and materials are suitable for tissue engineering applications.
Femtosecond laser fabrication of micro-tubes with a height of several tens of micrometers in the photopolymer SZ2080 by three different methods: direct laser writing, using the optical vortex beam and holographic lithography was demonstrated. The flexibility of direct laser writing and dramatic increase of production efficiency by applying the vortex-shaped beam and four-beam interference approaches are presented. Sample arrays of micro-tubes were successfully manufactured applying all three methods and the fabrication quality as well as efficiency of the methods is compared. The processing time of a single micro-tube with 60 μm height and 3 μm inner radius is reduced 400 times for the holographic lithography technique and 500 times for the optical vortex method compared with the direct laser writing technique. The processing time of a micro-tube array containing 400 micro-tubes is the shortest for the holographic lithography method but not for the optical vortex method as in the case of a single micro-tube, because the holographic lithography method does not require time for sample translation. Additionally, the holographic lithography enables manufacturing of the whole micro-tube array by a single exposure. Although point-by-point photo-structuring ensures unmatched complexity of manufactured microstructures, employing nowadays high repetition rate amplified femtosecond lasers combined with beam shaping or several beam interference can envisage industrial applications for practical demands.
Optimal structuring parameters for multi-photon polymerization fabrication technique for biomedical applications were defined in different polymeric materials using various lasers with different pulse durations (8 ps, 300 fs, 80 fs) and excitation wavelengths (532 nm, 515 nm and 800 nm). The applied photopolymers were: acrylate based AKRE, hybrid organic-inorganic Ormocore b59 and SZ2080, biodegradable PEG-DA-258 mixed with radical polymerization photoinitiators optimized for specific exposure conditions. It was defined that photoinitiators’ molecules did not affect materials cytotoxicity. Biocompatibilities of the used materials were investigated and showed positive results in vitro and in vivo. Furthermore, various in size and form artificial scaffolds were designed and fabricated as sample prototype implant structures for further experiments for tissue engineering applications in cardiovascular surgery.
Multi-photon polymerization system based on diode-pumped solid state femtosecond Yb:KGW laser used as pulsed irradiation light source (300fs,1030nm, 200 kHz) in combination with large area high sample translation velocity (up to 300mm/s) linear motor-driven stages (100x100x50 mm3) was designed for high resolution and throughput 3D micro/ nanofabrication. It enables rapid prototyping out of most polymers up to cm in scale with sub-micrometer spatial resolution. This can be used for production of three-dimensional artificial polymeric scaffolds applied for cell growth and expansion experiments as well as tissue engineering. Biocompatibilities of different acrylate, hybrid organic–inorganic and biodegradable polymeric materials were evaluated experimentally in vitro. Various in size and form scaffolds of biocompatible photopolymers were successfully fabricated having intricate 3D geometry, thus demonstrating the potential of the applied method. Adult rabbit myogenic stem cell proliferation tests show artificial scaffolds to be applicable for biomedical practice. Additionally, a micromolding technique was used for a rapid multiplication of adequate laser manufactured structures.

Projects Supported by Lithuanian Agency for Science, Innovation and Technology (MITA)

Essential Improvement in Group of Most Important Laser Elements by Enhancement of Optical Resistance and Optimization of Polishing and Metal Oxide Mixture Deposition Technologies (EIGULYS). 2011–2013.

Development and Implementation of Carrier-Envelope Phase Control in OPCPA Systems (PHASECONTROL). 2011–2013.

Development and Research of the Synchronously Pumped Femtosecond Optical Parametric Oscillator (MEGAOPO). 2012–2013.

Creation of Biologically Active Regular Three-Dimensional Structures for Tissue Molecular Bioengineering (BIO-MATRIX). 2012–2013.

Projects Supported by the Research Council of Lithuania

Femtosecond Digital Holography for Nonlinear Processes Investigation in Group III Nitride Compounds (FEDI). 2011–2012.

Growth of Single-Layer in Gan and Study its Optical Resistance with Ultrashort Laser Pulses (SIGNALAS). 2011–2012.

Extreme Events in Femtosecond White-Light Filamentation (EXFIL). 2011–2012.

Fabrication of Micro/Nanooptical Elements by Means of Laser and Electron Beam Lithographies (MIKROŠVIESA). 2012–2014.

International Science Programmes and Projects

7 FP Project: Integrated European Laser Laboratories III (LASERLAB-Europe III). 2012–2015.

7 FP Project: Integrated European Laser Laboratories II (LASERLAB-Europe II). 2009–2012.

7 FP Project: The Development Project for A Cheap, Innovative Ultra Thin Conductive Ceramic Mesh to Monitor Stress and Wear on a Steel Surface (Mesmesh, FP7-NMP- 2008-SME-2 No CP-TP 22099-2). 2009–2012.

Projects Supported by Structural Funds of EC

Project: Establishment of the Multi-Functional Laser Facility (NAGLIS). 2010–2012.

MAIN PUBLICATIONS

Monographs, Studies

P. Jucevičienė, D. Gudaitytė, V. Karenauskaitė, D. Lipinskienė, B. Stanikūnienė, G. Tautkevičienė. Universiteto edukacinė galia : atsakas XXI amžiaus iššūkiams : mokslo monografija. Kaunas : Technologija, 2010. 923 p.

Articles

P. Stanislovaitis, V. Smilgevičius. Control of optical vortex dislocations using optical methods // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 4, p. 295-300.

P. Danilevičius, S. Rekštytė, E. Balčiūnas, A. Kraniauskas, R. Širmenis, D. Baltriukienė, M. Malinauskas, V. Bukelskienė, R. Gadonas, V. Sirvydis, A. Piskarskas. Direct Laser Fabrication of Polymeric Implants for Cardiovascular Surgery // Materials science = Medžiagotyra / Kaunas University of Technology, Academy of Sciences of Lithuania. Kaunas : Technologija. 2012, vol. 18, no. 2, p. 145-149.

D. Paipulas, A. Balskienė, V. Sirutkaitis. Experimental study of filamentation and supercontinuum generation in laser-modified fused silica // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 4, p. 327-333.

R. Buividas, M. Mikutis, T. Kudrius, A. Greičius, G. Šlekys, S. Juodkazis. Femtosecond laser processing - a new enabling technology // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 4, p. 301-311.

J. Adamonis, R. Antipenkov, J. Kolenda, A. Michailovas, A. Piskarskas, A. Varanavičius, A. Zaukevičius. Formation of flat-top picosecond pump pulses for OPCPA systems by cascade second harmonic generation // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 3, p. 193-202.

J. Lapienis, V. Žalgevičienė, S. Bagdonas, E. Zakarevičius, E. Žurauskas, G. Graželienė, J. Didžiapetrienė, R. Rotomskis. Microscopic evidence of placenta as a natural barrier for a photosensitizer // Veterinarija ir zootechnika / Lietuvos veterinarijos akademija. Kaunas : Lietuvos veterinarijos akademija. 2012, t. 60, p. 39-44.

M. Mangirdas, G. Kiršanskė, S. Rekešytė, T. Jonavičius, E. Kaziulionytė, L. Jonušauskas, A. Žukauskas, G. Roaldas, P. Algis. Nanophotonic lithography: a versatile tool for manufacturing functional three-dimensional micro-/nano-objects // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 4, p. 312-326.

G. Abromavičius, R. Buzelis, R. Drazdys, K. Juškevičius, S. Kičas, T. Tolenis, J. Mirauskas, M. Ščiuka, V. Sirutkaitis, A. Melninkaitis. Optical resistance and spectral properties of anti-reflective coatings deposited on LBO crystals by ion beam sputtering // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2011, vol. 51, no. 4, p. 303-308.

J. Galinis, M. Karpinski, G. Tamošauskas, K. Dobek, A. Piskarskas. Photon correlation and statistics of spontaneous parametric down-conversion pumped by blue LED in LiIO3 crystal // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 4, p. 285-294.

V. Žalgevičienė, V. Kulvietis, D. Bulotienė, J. Didžiapetrienė, R. Rotomskis. The effect of nanoparticles in rats during critical periods of pregnancy // Medicina. Kaunas : Kauno medicinos universitetas. 2012, t. 48, nr. 5, p. 256-264.

J. Venius, S. Bagdonas, E. Žurauskas, R. Rotomskis. Time-resolved fluorescence spectroscopy of the heart tissues // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2011, Vol. 51, no. 4, p. 317-323.

L. Mažulė, S. Liukaitytė, R. Eckardt, A. Melninkaitis, O. Balachninaitė, V. Sirutkaitis. A system for measuring surface roughness by total integrated scattering // Journal of physics D: applied physics. Bristol : Institute of Physics Publishing Ltd. 2011, Vol. 44, no. 50, p. 505103 (9 p.).

C. Caruana, M. Wasilewska-Radwanska, A. Aurengo, P. Dendy, V. Karenauskaitė, M. Malisan, S. Mattson, J. Meijer, D. Mihov, V. Mornstein, E. Rokita, E. Vano, M. Weckstrom, M. Wucherer. A strategic development model for the role of the biomedical physicist in the education of healthcare professionals in Europe // Physica medica. Oxford : Elsevier Ltd. 2012, Vol. 28, no. 4, p. 307-318.

A. Urniežius, N. Šiaulys, V. Kudriašov, V. Sirutkaitis, A. Melninkaitis. Application of time-resolved digital holographic microscopy in studies of early femtosecond laser ablation // Applied physics. A. Materials science & processing. Heidelberg : Springer. 2012,, p.

D. Faccio, G. Tamošauskas, E. Rubino, J. Darginavičius, D. Papazoglou, S. Tzortzakis, A. Couairon, A. Dubietis. Cavitation dynamics and directional microbubble ejection induced by intense femtosecond laser pulses in liquids // Physical review. E : statistical physics, plasmas, fluids, and related interdisciplinary topics. College Park : American Physical Society. 2012, vol. 86, no. 3, art. no. 036304(6 p.).

A. Žukauskas, M. Malinauskas, C. Reinhardt, B. Chichkov, R. Gadonas. Closely packed hexagonal conical microlens array fabricated by direct laser photopolymerization // Applied optics. Washington : Optical Society of America. 2012, Vol. 51, no. 21, p. 4995-5003.

B. Mangote, L. Gallais, M. Commandre, M. Mende, L. Jensen, H. Ehlers, M. Jupe, D. Ristau, A. Melninkaitis, J. Mirauskas, V. Sirutkaitis, S. Kičas, T. Tolenis, R. Drazdys. Control of light polarization by acousto-optic diffraction from leaky acoustic wave in LiNbO3 // Optics letters. Washington : Optical Society of America. 2012, vol. 37, no. 9, p. 1478-1480.

V. Mizeikis, V. Purlys, D. Paipulas, R. Buividas, S. Juodkazis. Direct Laser Writing: Versatile Tool for Microfabrication of Lithium Niobate // Journal of Laser Micro / Nanoengineering. Osaka : Japan Laser Processing Society. 2012, Vol. 7, no. 3, p. 345-350.

D. Pentaris, T. Efthimiopoulos, N. Merlemis, V. Vaičaitis, A. Lyras. Emissions from high-density potassium atoms excited by either nanosecond or femtosecond laser pulses // Applied physics B. Lasers and optics. New York : Elsevier Science Inc. 2012, Vol. 107, no. 1, p. 71-83.

I. Dumbrytė, L. Linkevičienė, M. Malinauskas, T. Linkevičius, V. Pečiulienė, K. Tikuišis. Evaluation of enamel micro-cracks characteristics after removal of metal brackets in adult patients // European Journal of Orthodontics. Oxford : Oxford University Press. 2011,, p.

E. Stankevičius, T. Gertus, M. Rutkauskas, . Gedvilas, G. Račiukaitis, R. Gadonas, V. Smilgevičius, M. Malinauskas. Fabrication of micro-tube arrays in photopolymer SZ2080 by using three different methods of a direct laser polymerization technique // Journal of Micromechanics and Microengineering: structures, devices & systems. Bristol : Institute of Physics Publishing Ltd. 2012, Vol. 22, iss. 6, art. no. 065022(9 p.).

V. Pyragaitė, A. Stabinis, A. Piskarskas. Frequency spectrum of second-harmonic radiation excited by a Gaussian Schell-model beam // Physical review. A. Washington : American Physical Society. 2012, vol. 86, no. 3, p. 033812(8 p.).

J. Darginavičius, N. Garejev, A. Dubietis. Generation of carrier-envelope phase-stable two optical-cycle pulses at 2 Ī¼m from a noncollinear beta-barium borate optical parametric amplifier // Optics letters. Washington : Optical Society of America. 2012, Vol. 37, no. 22, p. 4805-4807.

J. Darginavičius, G. Tamošauskas, A. Piskarskas, G. Valiulis, A. Dubietis. Generation of tunable few optical-cycle pulses by visible-to-infrared frequency conversion // Applied physics B. Lasers and optics. New York : Elsevier Science Inc. 2012, vol. 108, no. 1, p. 1-7.

J. Adamonis, R. Antipenkov, J. Kolenda, A. Michailovas, A. Piskarskas, A. Varanavičius. High-energy Nd : YAG-amplification system for OPCPA pumping // Quantum electronics. London : Turpion Ltd. 2012, Vol. 42, no. 7, p. 567-574.

N. Šiaulys, V. Kudriašov, T. Stanislauskas, T. Malinauskas, A. Urniežius, A. Melninkaitis. Holographic study of ultrafast optical excitation in GaN film induced by nonlinear propagation of light // Optics letters. Washington : Optical Society of America. 2012, Vol. 37, no. 23, p. 4916-4918.

M. Malinauskas, D. Baltriukienė, A. Kraniauskas, P. Danilevičius, R. Jarašienė, R. Širmenis, A. Žukauskas, E. Balčiūnas, V. Purlys, R. Gadonas, V. Bukelskienė, V. Sirvydis, A. Piskarskas. In vitro and in vivo biocompatibility study on laser 3D microstructurable polymers // Applied physics. A. Materials science & processing. Heidelberg : Springer. 2012, Vol. 108, no. 3, p. 751-759.

V. Poderys, M. Matulionytė, A. Selskis, R. Rotomskis. Interaction of Water-Soluble CdTe Quantum Dots with Bovine Serum Albumin // Nanoscale Research Letters. Heidelberg : SpringerOpen. 2011, Vol. 9, Art. no. 6 (6 p.).

X. Fu, A. Melninkaitis, L. Gallais, S. Kiačas, R. Drazdys, V. Sirutkaitis, M. Commandre. Investigation of the distribution of laser damage precursors at 1064 nm, 12 ns on Niobia-Silica and Zirconia-Silica mixtures // Optics express. Washington : Optical Society of America. 2012, Vol. 20, no. 23, p. 26089-26098.

M. Malinauskas, A. Žukauskas, K. Belazaras, K. Tikuišis, V. Purlys, R. Gadonas, A. Piskarskas. Laser fabrication of various polymer micro-optical components // European physical journal. Applied physics. Paris : EDP Sciences. 2012,, p.

B. O'Regan, D. Nikogosyan, D. Paipulas, V. Kudriašov, V. Sirutkaitis. Long-period grating inscription in hydrogen-free SMF-28 fiber by high-repetition-rate femtosecond UV pulses // Optical Fiber Technology. Maryland Heights : Academic Press. 2012, Vol. 8, iss. 2, p. 88-92.

P. Danilevičius, S. Rekštytė, E. Balčiūnas, A. Kraniauskas, R. Jarašienė, R. Širmenis, D. Baltriukienė, V. Bukelskienė, R. Gadonas, M. Malinauskas. Micro-structured polymer scaffolds fabricated by direct laser writing for tissue engineering // Journal of biomedical optics. Bellingham : SPIE. 2012, Vol. 17, no. 8, art. no. 081405 (1-7).

J. Galinis, G. Tamošauskas, A. Piskarskas. Modeling of photon coincidence and dispersive properties of spontaneous parametric down-converted field excited by incoherent source // Optics communications. Amsterdam : Elsevier Science BV. 2012, vol. 285, iss. 6, p. 1289-1296.

S. Markov, V. Nagirnyi, A. Vasil'ev, V. Makhov, R. Laasner, S. Vielhauer, M. Kirm, R. Grigonis, V. Sirutkaitis. Modelling of decay kinetics of self-trapped exciton luminescence in CdWO4 under femtosecond laser excitation in absorption saturation conditions // Central European journal of physics. Warsaw : Versita. 2012, Vol. 10, no. 4, p. 1002-1008.

D. Faccio, E. Rubino, A. Lotti, A. Couairon, A. Dubietis, G. Tamošauskas, D. Papazoglou, S. Tzortzakis. Nonlinear light-matter interaction with femtosecond high-angle Bessel beams // Physical review. A. Washington : American Physical Society. 2012, vol. 85, no. 3, p. 033829(1-6).

J. Adamonis, R. Antipenkov, J. Kolenda, A. Michailovas, A. Piskarskas, A. Varanavičius. Picosecond pulse contrast enhancement by use of polarization rotation in crystals with the second-order nonlinearity // Applied physics B. Lasers and optics. New York : Elsevier Science Inc. 2012, vol. 106, no. 2, p. 321-326.

S. Toliautas, J. Šulskus, L. Valkūnas, M. Vengris. Quantum chemical studies of photochromic properties of benzoxazine compound // Chemical physics. Amsterdam : Elsevier Science. 2012, Vol. 404, p. 64-73.

V. Jukna, D. Majus, G. Valiulis, A. Dubietis. Radiation from band-gap solitons // Optics communications. Amsterdam : Elsevier Science BV. 2012, vol. 285, iss. 17, p. 3654-3658.

E. Gaižauskas, A. Savickas, K. Staliūnas. Radiation from band-gap solitons // Optics communications. Amsterdam : Elsevier Science BV. 2012, vol. 285, iss. 8, p. 2166-2170.

E. Gaubas, T. Čeponis, A. Uleckas, R. Grigonis. Room temperature spectroscopy of deep levels in junction structures using barrier capacitance charging current transients // Journal of instrumentation. Bristol : IOP Publishing Ltd. 2011, Vol. 6, p. art. no P01003 (1-9). [vėluojanti].

A. Matijoška, T. Charkova, Z. Kuodis, V. Voiciuk, O. Eicher-Lorka. Synthesis and properties of new biotin compounds containing hexyltriethylene glycol chain // Central European journal of chemistry. Warsaw : Versita, co-published with Springer-Verlag GmbH. 2012, vol. 10, no. 1, p. 113-120.

T. Gertus, M. Mikutis, P. Každailis, R. Rimeika, D. Čiplys, V. Smilgevičius. Surface acoustic wave phononic crystal device fabricated by femtosecond laser ablation // Microwave and Optical Technology Letters. Hoboken : John Wiley & Sons, Inc. 2012, Vol. 54, no. 5, p. 1286-1287.

M. Malinauskas, A. Žukauskas, V. Purlys, A. Gaidukevičiūtė, Z. Balevičius, A. Piskarskas, C. Fotakis, S. Pissadakis, D. Gray, R. Gadonas, M. Vamvakaki, M. Farsari. 3D microoptical elements formed in a photostructurable germanium silicate by direct laser writing // Optics and Lasers in Engineering. Oxford : Elsevier Ltd. 2012, Vol. 50, no. 12, p. 1785-1788.

Materials of conferences

S. Ragaišis, A. Birštunas, A. Mitašiūnas, V. Stočkus. Electronic Archive Information System // Databases and information systems : 10th international Baltic conference; local proceedings, July 8-11, 2012, Lithuania / edited by Albertas Čaplinskas, Gintautas Dzemyda, Audronė Lupeikienė, Olegas Vasilecas. Vilnius : Žara, 2012, p. 107-114.

L. Gallais, B. Mangote, M. Commandre, M. Mende, L. Jensen, H. Ehlers, M. Jupe, D. Ristau, A. Melninkaitis, V. Sirutkaitis, S. Kičas, T. Tolenis, R. Drazdys. An exhaustive study of laser damage in ion beam sputtered pure and mixture oxide thin films at 1030 nm with 500 fs pulse durations // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 85300K(8 p.).

A. Melninkaitis, M. Ščiuka, G. Batavičiūtė, J. Mirauskas, S. Bucka, V. Sirutkaitis. Automated test station for characterization of optical resistance with ultrashort pulses at multikilohertz repetition rates // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 85301M(10 p.).

G. Batavičiūtė, P. Grigas, L. Smalakys, A. Melninkaitis. Bayesian approach of laser-induced damage threshold analysis and determination of error bars // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 85301S(12 p.).

S. Liukaitytė, G. Batavičiūtė, E. Pupka, M. Ščiuka, I. Kraujalienė, D. Tumosa, A. Skrebutėnas, K. Juškevičius, T. Tolenis, S. Kičas, R. Drazdys, R. Buzelis, A. Melninkaitis. Effect of conventional fused silica preparation and deposition techniques on surface roughness, scattering, and laser damage resistance // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 853027(12 p.).

J. Darginavičius, G. Tamošauskas, G. Valiulis, A. Piskarskas, A. Dubietis. Generation of Sub-30 fs Tunable Infrared Pulses by Parametric Visible-to-Infrared Frequency Conversion // Light at Extreme Intensities 2011, Szeged, Hungary, 14-18 November 2011. Book series : AIP Conference Proceedings. Vol. 1462. ISSN 0094-243X. Melville : American Institute of Physics, 2012, p. 92-95.

E. Stankevičius, E. Balčiūnas, M. Malinauskas, G. Račiukaitis, D. Baltriukienė, V. Bukelskienė. Holographic lithography for biomedical applications // Proceedings of SPIE. 2012, Vol. 8433 : Laser Sources and Applications / eds.: Thomas Graf, Jacob I. Mackenzie, Helena Jelenkova, John Powell, p. 843312(7 p.).

T. Malinauskas, A. Kadys, T. Grinys, S. Nargelas, R. Aleksiejūnas, S. Miasojedovas, J. Mickevičius, R. Tomašiūnas, K. Jarašiūnas, M. Vengris, S. Okur, V. Avrutin, X. Li, F. Zhang, U. Ozgur, H. MorkoĆ§. Impact of carrier localization, recombination, and diffusivity on excited state dynamics in InGaN/GaN quantum wells // Proceedings of SPIE. Bellingham : SPIE. 2012, vol. 8262 : Gallium Nitride Materials and Devices VII / editors: Jen-Inn Chyi, Yasushi Nanishi, Hadis MorkoĆ§, Joachim Piprek, Euijoon Yoon. ISBN 9780819489050. p. 82621S (10 p.).

E. Balčiūnas, L. Jonušauskas, V. Valuckas, D. Baltriukienė, V. Bukelskienė, R. Gadonas, M. Malinauskas. Lithographic microfabrication of biocompatible polymers for tissue engineering and lab-on-a-chip applications // Proceedings of SPIE. 2012, vol. 8427 : Biophotonics: photonic solutions for better health care III / editors: Jurgen Popp, Wolfgang Drexler, Valery V. Tuchin, Dennis L. Matthews. ISBN 9780819491190. p. 84271X(9 p.).

X. Fu, A. Melninkaitis, L. Gallais, S. Kičas, R. Drazdys, V. Sirutkaitis, M. Commandre. Measured nanosecond laser damage probabilities of niobia-silica and zirconia-silica mixtures coatings // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 85300X(7 p.).

M. Ščiuka, M. Dmukauskas, T. Grinys, A. Melninkaitis. Optical resistance of GaN and InGaN thin films // Proceedings of SPIE. Bellingham : SPIE. 2012, Vol. 8530 : Laser-Induced Damage in Optical Materials: Boulder, Colorado, USA, September 23, 2012 / edited by Gregory J. Exarhos, Vitaly E. Gruzdev, Joseph A. Menapace, Detlev Ristau, M J Soileau. p. 85300Y(10 p.).

A. Žukauskas, K. Tikuišis, M. Ščiuka, A. Melninkaitis, R. Gadonas, C. Reinhardt, M. Malinauskas. Single-step direct laser fabrication of complex shaped microoptical components // Proceedings of SPIE. 2012, Vol. 8428 : Micro-Optics 2012 (ISBN 9780819491206), p. 84280K(9 p.).

B. Mangote, L. Gallais, M. Zerrad, M. Commandre, L. Gao, F. Lemarchand, M. Lequime, A. Melninkaitis, J. Mirauskas, V. Sirutkaitis, S. Kičas, T. Tolenis, R. Drazdys, M. Mende, L. Jensen, H. Ehlers, D. Ristau. Study of the laser matter interaction in the femtosecond regime: application to the analysis of the laser damage of optical thin films // Proceedings of SPIE. 2011, Vol. 8168 : Advances in Optical Thin Films IV / Editors: Michel Lequime, H. Angus Macleod, Detlev Ristau. p. 816815 (10 p).

T. Suzuki, J. Morikawa, T. Hashimoto, R. Buividas, G. Gervinskas, D. Paipulas, M. Malinauskas, V. Mizeikis, S. Juodkazis. Thermal and optical properties of sol-gel and SU-8 resists // Proceedings of SPIE. 2012, vol. 8249 : Advanced Fabrication Technologies for Micro/Nano Optics and Photonics V / edited by Winston V. Schoenfeld, Raymond C. Rumpf, Georg von Freymann. p. 82490K (9 p).

L. Maigytė, J. Trull, V. Mizeikis, M. Malinauskas, S. Juodkazis, C. Cojocaru, M. Rutkauskas, M. Peckus, V. Sirutkaitis, K. Staliūnas. Woodpile photonic crystal for beam collimation // Proceedings of SPIE. 2012, vol. 8425 : Photonic Crystal Materials and Devices X / Editors: Hernan R. Meguez, Sergei G. Romanov, Lucio C. Andreani, Christian Seassal. ISBN 9780819491176. p. 842511 (7 p).

V. Mizeikis, V. Purlys, D. Paipulas, R. Buividas, S. Juodkazis. Direct laser writing: versatile tool for microfabrication of lithium niobate // Proceedings of LPM2012 : 13th International Symposium on Laser Precision Microfabrication, June 12-15, 2012, Washington, USA. Washington : The Catholic University of America, 2012, [6 p.].

A. Urniežius, N. Šiaulys, V. Kudriašov, V. Sirutkaitis, A. Melninkaitis. Investigation of the Femtosecond Laser Ablation by Time-resolved Digital Holography // Proceedings of LPM2012 : 13th International Symposium on Laser Precision Microfabrication, June 12-15, 2012, Washington, USA. Washington : The Catholic University of America, 2012, [6 p.].

A. Baškevičius, A. Alesenkov, G. Chozevskis, J. Litvaitytė, O. Balachninaitė, D. Paipulas, A. Melninkaitis, V. Sirutkaitis. Optimization of laser-ablation micromachining by choice of scanning algorithms and use of laser-induced-breakdown spectroscopy // Proceedings of LPM2012 : 13th International Symposium on Laser Precision Microfabrication, June 12-15, 2012, Washington, USA. Washington : The Catholic University of America, 2012, [6 p.].

V. Vaičaitis, V. Smilgevičius, E. Gaižauskas, V. Jarutis, D. Chomčik. Six-wave mixing in terahertz wave generation from laser-induced air plasma // TST 2012 : 3rd EOS Topical Meeting on Terahertz Science & Technology, Prague, Czech Republic, 17-20 June 2012. Prague : European Optical Society, 2012, [2 p.].

J. Darginavičius, G. Tamošauskas, G. Valiulis, A. Piskarskas, A. Dubietis. Generation of tunable infrared femtosecond pulses via parametric visible-to-infrared frequency conversion // Advanced solid-state photonics : Lasers, sources, and related photonic devices technical digest, 29 January - 3 February 2012, California, USA. Washington : Optical Society of America, 2012, p.

A. Zaukevičius, V. Jukna, R. Antipenkov, V. Martinėnaitė, A. Varanavičius, A. Piskarskas, G. Valiulis. Spatial chirp and angular dispersion dynamics in femtosecond noncollinear OPCPA // Advanced solid-state photonics : Lasers, sources, and related photonic devices technical digest, 29 January - 3 February 2012, California, USA. Washington : Optical Society of America, 2012, p.

COOPERATION

With over 20 Universities and Research Centres in the European Union.

OTHER SCIENTIFIC ACTIVITIES

Prof. A. Piskarskas –

President of Lithuanian Association of Laser Science and Technologies;
member of the Lithuanian Academy of Sciences;
member of the Optical Society of America.

Prof. A. Stabinis –

member of the Lithuanian Academy of Sciences;
editorial board member of the Lithuanian Journal of Physics;
editorial board member of the Terminology.

Prof. R. Rotomskis –

member of the Scientific Advisory Committee of the International Forum for virtual conferences Internet Photochemistry and Photobiology;
member of the Council of the European Society for Photobiology, Executive Representative of Photobiology Sciences for East European countries;
national representative of the Mirror Group of ETP Nanomedicine.

Prof. V. Sirutkaitis –

member of the MITA Council on High Technologies;
member of Access Board Laserlab 2;
member of Access Board Laserlab 3;
member of SPIE.

Dr. A. Dubietis –

member of the Optical Society of America;
member of the International Meteor Organization.

Dr. V. Karenauskaitė –

member of the SIG Biomedical Physics Education for the Healthcare Professions of the EFOMP (European Federation of Organizations for Medical Physics);
member of working group ERASMUS Academic Network STEPS (Stakeholders tune European physics studies) TWO.

DEPARTMENT OF SOLID STATE ELECTRONICS

9 Saulėtekio, LT-01513 Vilnius
Tel. 236 6061, fax. 236 6003
E-mail

Head – Doc. Dr. Kęstutis Arlauskas

STAFF

Professors: Dr. K. Arlauskas, Habil. Dr. G. Juška, Habil. Dr. P. J. Žilinskas, Habil. Dr. A.Undzenas (part time), Dr. V. Karpus (part time).
Docents: Dr. A. Pažėra (part time), Dr. A. Poškus, Dr. M. Viliūnas, Dr. S. Vengris (part time), Dr. V. Jankauskas (part time), Dr. R. Maldžius (part time).
Senior research fellows: Habil. Dr. V. Gaidelis, Habil. Dr. T. Lozovski, Dr. R. Purlys, Dr. R. Rinkūnas, Dr. K. Genevičius, Dr. N. Nekrašas, Dr. V. Jankauskas (part time), Dr. R. Maldžius (part time), Dr. J. Sidaravičius (part time), Dr. G. Sliaužys.
Junior research fellow: J. Jurkšus.
Doctoral students: E. Jakubovskij, T. Grigaitis, A. Naujokaitis, E. Kamarauskas, V. Sabonis.

RESEARCH INTERESTS

Features of charge carrier transport and recombination in disordered structures
Deposition and investigation of non-crystalline, organic polymer and hybrid layers for organic electronics: solar cells, field effect transistors, organic light emitting diodes
Investigation of electrical and dielectric properties of paper and chemicals
Technology and application of carbon nanotubes
Generation and transport of vacancies in crystalline silicon

RESEARCH PROJECTS CARRIED OUT IN 2012

Project Supported by University Budget

Technology, Dielectric and Optoelectronic Features of Organic-Inorganic Structures. Prof. G. Juška. 2008–2012.

Photo-CELIV extraction current transients of photogenerated charge carriers have been numerically modelled in case of reduced Langevin recombination and obtained results applied for investigation of charge carrier properties in bulk heterojunction layers.
Proposed method of injected charge carrier extraction current transients (i-CELIV), which was used for investigation of charge carrier reservoir in the TiO2/RR-P3HT:PCBM interface.
Influence of charge carrier diffusion onto extraction current transients has been numerically modelled.
Charge carrier injection and extraction current transients using linearly increasing voltage have been experimentally investigated, and current transients of channel formation in MDS structures have been numerically modelled.
Technology of deposition of organic light diode structures in vacuum has been prepared and two emitting organic material OLED test structure, which emitted in 450–750 nm wavelength region (white light), has been deposited and investigated.
Hybrid organic-inorganic layers have been formed using thermal melting and electric, photoelectric features of these layers have been investigated.
Two-dimensional electrostatic potential distribution in the “organic photoreceptor-toner-paper” system transfer nip for the special purpose paper (mixtures of cellulose and corresponding salts, chalks and with special surface coating) has been determined. The results were summarized relatively to the Paschen discharge effect. Numerical modelling method was adapted to the paper with different amount of hemicelluloses.
Charge transfer from a needle onto a non conductive layer was investigated. E-spinning process was also investigated using “ball-testing” method.
Ionization potential of the new organic materials for optoelectronics was investigated.
Possibility of formation of vacancies using X-rays and electric field in crystalline silicon have been investigated.

EU Project

7FP project: A Marie Curie international training network and research project ESTABLIS (FP7-PEOPLE-2011-ITN, No. 290022). Supervisor: Prof. G. Juška. EU. 2012–2015.

Projects, Programs, Issues Supported by the Research Council of Lithuania

The Influence of Nano-Morphology to Charge Carrier‘S Dynamics. Prof. G. Juška. 2011– 2014.

Ordered Research Projects

Research Cooperation Contract: Omega. Coordinators: Stora Enso Oyj, Finland, Prof. G. Juška, VU, Lithuania. 2012.

Consulting Agreement: BASF. Coordinators: BASF-The Chemical Company, Germany, Dr. V. Jankauskas, VU, Lithuania. 2012.

MAIN PUBLICATIONS

Articles

P. Žilinskas. Dar kartą apie Šlapelius Patagonijoje // Kupiškis : kultūra ir istorija. Vilnius : Vilniaus dailės akademijos leidykla. 2012, Nr. 10, p. 37-41.

P. Žilinskas. Kupiškėnai - Patagonijos kolonizatoriai // Kupiškis : kultūra ir istorija. Vilnius : Vilniaus dailės akademijos leidykla. 2010, Nr. 9, p. 44-48.

P. Žilinskas. Kupiškėnas - sukilėlis, pirmasis Argentinos miesto Sarmiento gyventojas // Kupiškis : kultūra ir istorija. Vilnius : Vilniaus dailės akademijos leidykla. 2010, Nr. 8, p. 48-52.

S. Urnikaitė, T. Malinauskas, V. Gaidelis, V. Jankauskas, V. Getautis. Air-Stable, Narrow-Band-Gap Ambipolar C60 Fullerene-Hydrazone Hybrid Materials // Chemistry - An Asian Journal. Weinheim : Wiley - VCH Verlag GmbH & Co. KGaA. 2012, Vol. 7, iss. 3, p. 614-620.

J. Kaladė, R. Maldžius, J. Sidaravičius, P. Sirvio, K. Backfolk. Dependence of electrostatic field strength on image transfer roller dimensions in a toner transfer region // Journal of imaging science and technology. Springfield : Society for Imaging Science and Technology. 2012, vol. 56, no. 1, p. Art no. 010504 (1-8).

A. Tomkevičienė, G. Puckytė, J. Gražulevičius, K. Kazlauskas, S. Juršėnas, V. Jankauskas. Dimethyldiphenylamino-substituted carbazoles as electronically active molecular materials // Dyes and pigments. Oxford : Elsevier Science LTD. 2012, Vol. 96, no. 2, p. 574-580.

A. Tomkevičienė, G. Puckytė, J. Gražulevičius, M. Degbia, F. Tran-Van, B. Schmaltz, V. Jankauskas, J. Boucle. Diphenylamino-substituted derivatives of 9-phenylcarbazole as glass-forming hole-transporting materials for solid state dye sensitized solar cells // Synthetic metals. Lausanne : Elsevier Science SA. 2012, vol. 162, iss. 23, p. 1997-2004.

A. Armin, G. Juška, B. Philippa, P. Burn, P. Meredith, R. White, A. Pivrikas. Doping-induced screening of the built-in-field in organic solar cells: effect on charge transport and recombination // Advanced energy materials. Weinheim : Wiley - V C H Verlag GmbH & Co. KGaA. 2012, vol. p.

S. Sanden, O. Sandberg, Q. Xu, W. Chin, J. Smatt, G. Juška, M. Linden, R. Osterbacka. Effect of a large hole reservoir on the charge transport in TiO2/organic hybrid devices // Physical chemistry chemical physics. Cambridge : Royal Society of Chemistry. 2012, Vol. 14, iss. 40, p. 14186-14189.

V. Nekrašas, K. Genevičius, V. Viliūnas, G. Juška. Features of current transients of photogenerated charge carriers, extracted by linearly increased voltage // Chemical physics. Amsterdam : Elsevier Science. 2012, Vol. 404, p. 56-59.

R. Reghu, J. Gražulevičius, J. Simokaitienė, A. Miasojedovas, K. Kazlauskas, S. Juršėnas, P. Data, K. Karon, M. Lapkowski, V. Gaidelis, V. Jankauskas. Glass-Forming Carbazolyl and Phenothiazinyl Tetra Substituted Pyrene Derivatives: Photophysical, Electrochemical, and Photoelectrical Properties // The Journal of Physical Chemistry C: Nanomaterials, Interfaces and Hard Matter. Washington : American Chemical Society. 2012, Vol. 116, no. 30, p. 15878-15887.

J. Keruckas, R. Lygaitis, J. Simokaitienė, J. Gražulevičius, V. Jankauskas, G. Sini. Influence of methoxy groups on the properties of 1,1-bis(4-aminophenyl) cyclohexane based arylamines: experimental and theoretical approach // Journal of Materials Chemistry. Cambridge : Royal Society of Chemistry. 2012, Vol. 22, iss. 7, p. 3015-3027.

G. Juška, N. Nekrašas, K. Genevičius. Investigation of charge carriers transport from extraction current transients of injected charge carriers // Journal of non-crystalline solids. Amsterdam : Elsevier BV * North-Holland. 2012, Vol. 358, iss. 4, p. 748-750.

R. Rinkūnas, P. Žilinskas, R. Purlys, S. Kuskevičius. Investigation of layers' sheet resistance using the spread of mobile charge carriers // Journal of electrostatics. Amsterdam : Elsevier Science BV. 2012, vol. 70, p. 419-427.

M. Čekavičiūtė, J. Simokaitienė, J. Gražulevičius, G. Buika, V. Jankauskas. New derivatives of indazole as electronically active materials // Dyes and pigments. Oxford : Elsevier Science LTD. 2012, vol. 92, no. 1, p. 654-658.

G. Sliaužys, K. Arlauskas, V. Gulbinas. Photogeneration and recombination of charge carrier pairs and free charge carriers in polymer/fullerene bulk heterojunction films // Physica status solidi A. Applications and Materials Science. Weinheim : WILEY-VCH Verlag GmbH & Co. 2012, vol. 209, no. 7, p. 1302-1306.

J. Simokaitienė, E. Stanislovaitytė, J. Gražulevičius, V. Jankauskas, R. Gu, W. Dehaen, Y. Hung, C. Hsu. Synthesis and Properties of Methoxyphenyl-Substituted Derivatives of Indolo[3,2-b]carbazole // Journal of organic chemistry. Washington : American Chemical Society. 2012, Vol. 77, iss. 11, p. 4924-4931.

V. Mimaitė, J. Gražulevičius, J. Ostrauskaitė, V. Jankauskas. Synthesis and properties of triphenylamine-based hydrazones with reactive vinyl groups/ // Dyes and pigments. Oxford : Elsevier Science LTD. 2012, vol. 95, no. 1, p. 47-52.

A. Bieliauskas, V. Martynaitis, V. Getautis, T. Malinauskas, V. Jankauskas, E. Kamarauskas, W. Holzer, A. Šačkus. Synthesis of electroactive hydrazones derived from 3-(10-alkyl-10H-phenothiazin-3-yl)-2-propenals and their corresponding 3,3-bispropenals // Tetrahedron. Oxford : Pergamon. 2012, vol. 68, iss. 18, p. 3552-3559.

D. Gudeika, A. Michalevičiūtė, J. Gražulevičius, R. Lygaitis, S. Grigalevičius, V. Jankauskas, A. Miasojedovas, S. Juršėnas, G. Sini. Structure Properties Relationship of Donor-Acceptor Derivatives of Triphenylamine and 1,8-Naphthalimide // The Journal of Physical Chemistry C: Nanomaterials, Interfaces and Hard Matter. Washington : American Chemical Society. 2012, Vol. 116, no. 28, p. 14811-14819.

Materials of conferences

J. Kaladė, E. Montrimas, R. Rinkūnas. Charge transfer from the needle electrode on the low-conductance layer surface // Radiation interaction with material and its use in technologies 2012 : 4rd international conference, Kaunas, Lithuania, May 14-17, 2012 : program and materials. Kaunas : Technologija, 2012, p. 585-588.

R. Rinkūnas, T. Lozovski, J. Jurkšus. Charge transfer from the needle electrode on the low-conductance layer surface // Radiation interaction with material and its use in technologies 2012 : 4rd international conference, Kaunas, Lithuania, May 14-17, 2012 : program and materials. Kaunas : Technologija, 2012, p. 581-584.

R. Purlys, M. Skrebkova, S. Balakauskas, A. Janavičius. Influence of anode voltage on X-ray-generated vacancies in quartz crystals // Radiation interaction with material and its use in technologies 2012 : 4rd international conference, Kaunas, Lithuania, May 14-17, 2012 : program and materials. Kaunas : Technologija, 2012, p. 153-156.

A. Janavičius, R. Purlys. Investigation of superdiffusion of metastable vacancies by bragg difraction of X-rays // Radiation interaction with material and its use in technologies 2012 : 4rd international conference, Kaunas, Lithuania, May 14-17, 2012 : program and materials. Kaunas : Technologija, 2012, p. 612-615.

A. Janavičius, A. Mekys, R. Purlys, Ž. Norgėla. Oxygen complexes with vacancies irradiated by soft X-rays in Cz silicon // Radiation interaction with material and its use in technologies 2012 : 4rd international conference, Kaunas, Lithuania, May 14-17, 2012 : program and materials. Kaunas : Technologija, 2012, p. 578-580.

G. Juška. Photo-CELIV technique for the investigations of charge carriers transport and recombination in the organic solar cells // Renewable energy and the environment congress : [proceedings], 11-14 November, 2012, Netherlands. Eindhoven, 2012, p.

J. Ardaravičienė, K. Arlauskas, K. Rakštys, V. Getautis. 1-fenil-1,2,3,4-tetrahidrochinolino-rodanino dažiklių sintezė bei jais aktyvuotų saulės elementų savybės // Organinė chemija = Organic chemistry : mokslinės konferencijos pranešimų medžiaga. Kaunas : Technologija, 2012, p. 72.

COOPERATION

Kaunas University of Technology, Kaunas (Lithuania)

Brisbane University, Brisbane (Australia)

Lappeenranta University, Lappeenranta (Finland)

Stora Enso Oyj (Finland)

BASF (Germany)

OTHER SCIENTIFIC ACTIVITIES

Prof. G. Juška –

editorial board member of the Lithuanian Journal of Physics;
referee of the journals Physica Status Solidi, Quantum Electronics.

Prof. P. J. Žilinskas –

editorial board member of the journal Matavimai (Measurements).

DEPARTMENT OF SEMICONDUCTOR PHYSICS

9 Saulėtekio, LT-10222 Vilnius
Tel. 236 6070, fax 236 6070
E-mail

Head – Prof. Habil. Dr. Gintautas Tamulaitis

STAFF

Professors: Habil. Dr. V. Gavriušinas (part-time), Habil. Dr. K. Jarašiūnas (part-time), Habil. Dr. S. Juršėnas (part-time), Habil. Dr. Ž. Kancleris (part-time), Habil. Dr. V. Kažukauskas (part-time), Habil. Dr. E. Kuokštis, Habil. Dr. L. Subačius (part-time), Dr. V. Tamošiūnas, Habil. Dr. G. Tamulaitis (part-time), Acad. Habil. Dr. J. V. Vaitkus (part-time), Dr. (HP) G. Valušis (part-time), Acad. Habil. Dr. A. Žukauskas (part-time).
Docents: Dr. R. Aleksiejūnas (part-time), Dr. R. Butkutė (part-time), Dr. I. Šimkienė (part-time), Dr. S. Tamošiūnas (part-time), Dr. V. Tamošiūnas (part-time), Dr. E. Žąsinas (part-time).
Lecturers: Dr. I. Kašalynas (part-time), Dr. A. Mekys (part-time), A. Arlauskas (part-time).
Senior research fellow: Dr. J. Storasta (part-time).
Research fellows: Dr. V. Kalendra (part-time), Dr. J. Mickevičius, Dr. R. Pūras.
Doctoral students: T. Čeponis, D. Dobrovolskas, K. Gulbinas, E. Jelmakas, J. Jurkevičius, M. Karaliūnas, G. Manolis, D. Meškauskas, A. Miasojedovas, S. Nargelas, J. Pavlov, M. Pranaitis, I. Reklaitis, V. Rumbauskas, T. Serevičius, L. Aleksandravičienė, M. Skapas, G. Statkutė, P. Ščajev, D. Ševčenko, A. Tekorius, A. Tuzikas, A. Uleckas.

RESEARCH INTERESTS

Spectroscopic characterization of novel inorganic and organic semiconductor materials for optoelectronics
Optical nonlinearities in semiconductors caused by free carriers, electrooptic and spin-related mechanisms
Dynamics of nonequilibrium carriers and excitons in highly excited semiconductors and their low-dimensional structures
Radiation detectors, high-density scintillation crystals
Applications of light emitting diodes
Computer simulation of crystal surface and defects

RESEARCH PROJECTS CARRIED OUT IN 2012

Projects, Supported by University Budget

Development of Materials, Structures and Devices for Topical Semiconductor Optoelectronics. Prof. K. Jarašiūnas, Prof. S. Juršėnas, Dr. R. Tomašiūnas. 2011–2014.

MOCVD technology for growth of nitrides, their multilayers and nanostructures was built up. GaN, InGaN, AlGaN layers were investigated by scanning electron (EDS, EBIC) and atomic force microscopy, optical (spectroscopy, luminescence, non-linear optical properties) and electrical (mobility) investigation. Orientational properties of materials with noncentrosymmetry (dendrimers, phenylcarbazoles) were investigated. Layered TlGaSe2, InSe and GaSe crystals and 3C-SiC structures were investigated by means of conventional and transient free-carrier absorption spectroscopy, photoacoustic deflection method.

International Science Programmes and Projects

COST Action MP0805 Project: Novel Gain Materials and Devices Based on III-V-N Compounds. Prof. G. Tamulaitis. 2010–2012.

Projects Funded by the Research Council of Lithuania

Enhancement of Light Emisssion Efficiency in Wide-Band-Gap Nitride Semiconductors. Dr. J. Mickevičius. 2012–2014.

Design and Investigation of Solid State Lighting Based Solar Simulator of a Class Spectrum. Prof. V. Tamošiūnas. 2012–2014.

MAIN PUBLICATIONS

Parts of the Books

G. Tamulaitis. Spatially resolved luminescence spectroscopy. Semiconductor research: experimental techniques / editors: Amalia Patane, Naci Balkan. - Springer series in material science. ISNN 0933-033X. Heidelberg : Springer, 2012, p. 197-222.

Articles

P. Vitta, L. Dabašinskas, A. Tuzikas, A. Petrulis, D. Meškauskas, A. Žukauskas. Concept of Intelligent Solid-State Street Lighting Technology // Elektronika ir elektrotechnika / Kauno technologijos universitetas. Kaunas : Technologija. 2012, vol. 18, nr. 10, p. 37-40.

V. Gavriušinas. Asymmetric double quantum wells with smoothed interfaces // Central European journal of physics. Warsaw : Versita. 2012, vol. 10, no. 2, p. 459-469.

G. Tamulaitis, J. Mickevičius, D. Dobrovolskas, E. Kuokštis, M. Shur, M. Shatalov, J. Yang, R. Gaska. Carrier dynamics and efficiency droop in AlGaN epilayers with different Al content // Physica status solidi C : Current topics in solid state physics. Weinheim : WILEY-VCH Verlag GmbH & Co. 2012, Vol. 9, iss. 7, p. 1677-1679.

A. Žukauskas, R. Vaicekauskas, M. Shur. Color-dulling solid-state cources of light // Optics express. Washington : Optical Society of America. 2012,Vol. 20, no. 9, p. 9755-9762.

L. Minkevičius, R. Suzanovičienė, S. Balakauskas, G. Molis, A. Krotkus, G. Valušis, V. Tamošiūnas. Detection of tab wire soldering defects on silicon solar cells using terahertz time-domain spectroscopy // Electronics letters. Hertford : Instutute of Engineering Technology. 2012, Vol. 48, no. 15, p. 932-934.

V. Kažukauskas, V. Kalendra, N. Vainorius, C. Bumby, B. Ludbrook, A. Kaiser. Electrical Properties of Composites of Polystyrene and Multi-Walled Carbon Nanotubes // Molecular crystals and liquid crystals. Abingdon : Taylor & Francis. 2012, vol. 556, iss. 1 : Special Issue: Proceedings of the 11th International Conference on Frontiers of Polymers and Advanced Materials (ICFPAM2011), p. 158-167.

M. Pranaitis, V. Kažukauskas. Energy Distribution of Trapping and Transport States in MDMO-PPV ([poly-(2-methoxyl, 5-(3,77dimethyloctyloxy)] Para Phenylenevinylene) // Journal of nanoscience and nanotechnology. Valencia : American Scientific Publishers. 2012, Vol. 12, no. 6, p. 4717-4723.

X. Li, S. Okur, F. Zhang, S. Hafiz, V. Avrutin, U. Ozgur, H. Morkoc, K. Jarašiūnas. Improved quantum efficiency in InGaN light emitting diodes with multi-double-heterostructure active regions // Applied physics letters. Melville: American Institute of Physics. 2012, vol. 101, iss. 4, p. Art. no 041115(4 p.).

J. Mickevičius, G. Tamulaitis, M. Shur, M. Shatalov, J. Yang, R. Gaska. Internal quantum efficiency in AlGaN with strong carrier localization // Applied physics letters. Melville: American Institute of Physics. 2012, vol. 101, iss. 21, Art. no 211902(4 p.).

V. Kažukauskas, M. Pranaitis. Non-Homogeneity of Distribution of Transport and Trapping States in Poly [2-methoxy-5-(3 ,7 -dimethyloctyloxy)-1,4-phenylenevinylene] // Journal of nanoscience and nanotechnology. Valencia : American Scientific Publishers. 2012, Vol. 12, no. 8, p. 6769-6773.

P. Ščajev, P. Onufrijevs, G. Manolis, M. Karaliūnas, S. Nargelas, N. Jegenyes, J. Lorenzzi, G. Ferro, M. Beshkova, R. Vasiliauskas, M. Syvajarvi, R. Yakimova, M. Kato, K. Jarašiūnas. On Applicability of Time-Resolved Optical Techniques for Characterization of Differently Grown 3C-SiC Crystals and Heterostructures // Materials science forum. Stafa-Zurich : Trans Tech Publications. 2012, vol. 711, p. 159-163.

P. Malinovskis, A. Mekys, A. Kadys, T. Malinauskas, T. Grinys, V. Bikbajevas, R. Tomašiūnas, J. Storasta, P. Malinovskis, P. Malinovskis, A. Mekys, A. Mekys, J. Storasta. Peculiarities of galvanomagnetic effects in GaN epilayers and GaN/InGaN quantum wells // Physica status solidi C : Current topics in solid state physics. Weinheim : WILEY-VCH Verlag GmbH & Co. 2012, Vol. 9, iss. 3-4, p. 689-692.

J. Mickevičius, J. Jurkevičius, M. Shur, J. Yang, R. Gaska, G. Tamulaitis. Photoluminescence efficiency droop and stimulated recombination in GaN epilayers // Optics express. Washington : Optical Society of America. 2012, Vol. 20, no. 23, p. 25195-25200.

J. Dodonova, L. Skardžiūtė, K. Kazlauskas, S. Juršėnas, S. Tumkevičius. Synthesis of 4-aryl-, 2,4-diaryl- and 2,4,7-triarylpyrrolo[2,3-d]pyrimidines by a combination of the Suzuki cross-coupling and N-arylation reactions // Tetrahedron. Oxford : Pergamon. 2012, vol. 68, iss. 1, p. 329-339.

J. Mickevičius, J. Jurkevičius, K. Kazlauskas, A. Žukauskas, G. Tamulaitis, M. Shur, M. Shatalov, J. Yang, R. Gaska. Stimulated emission due to localized and delocalized carriers in Al0.35Ga0.65N/Al0.49Ga0.51N quantum wells // Applied physics letters. Melville: American Institute of Physics. 2012, vol. 101, iss. 4, p. Art. no 041912(4 p.).

J. Mickevičius, J. Jurkevičius, K. Kazlauskas, A. Žukauskas, G. Tamulaitis, M. Shur, M. Shatalov, R. Gaska. Stimulated emission in AlGaN/AlGaN quantum wells with different Al content // Applied physics letters. Melville: American Institute of Physics. 2012, vol. 100, iss. 8, p. Art. no 081902(4 p.).

G. Tamulaitis, D. Dobrovolskas, J. Mickevičius, V. Kazlauskienė, J. Miškinis, E. Kuokštis, P. Onufrijevs, A. Medvids, J. Huang, C. Chen, C. Liao, C. Yang. Suppression of defect-related luminescence in laser-annealed InGaN epilayers // Physica status solidi C : Current topics in solid state physics. Weinheim : WILEY-VCH Verlag GmbH & Co. 2012, Vol. 9, iss. 3-4, p. 1021-1023.

V. Kažukauskas, M. Pranaitis, A. Sakavičius, O. Krupka, F. Kajzar, B. Sahraoui. Temperature Dependence of the Bistable Photoconductivity of Thin DNA: PEDOT Films // Molecular crystals and liquid crystals. Abingdon : Taylor & Francis. 2012, vol. 554, iss. 1 : Special Issue: Proceedings of the 11th International Conference on Frontiers of Polymers and Advanced Materials (ICFPAM2011), p. 83-94.

M. Žilinskas, M. Tamošiūnaitė, M. Tamošiūnienė, E. Valma, S. Tamošiūnas. Gradient of Radio Refractivity in Troposphere // PIERS 2012 Moscow : Progress In Electromagnetics Research Symposium, August 19-23, 2012, Moscow, Russia : proceedings. ISSN 1559-9450. Cambridge : The Electromagnetics Academy, 2012, p. 603-607.

Materials of conferences

A. Lisauskas, S. Boppel, M. Saphar, V. Krozer, L. Minkevičius, R. Venckevičius, D. Seliuta, I. Kašalynas, V. Tamošiūnas, G. Valušis, H. Roskos. Detectors for terahertz multi-pixel coherent imaging and demonstration of real-time imaging with a 12x12-pixel CMOS array // Proceedings of SPIE. Bellingham : SPIE. 2012, vol. 8496 : Terahertz emitters, receivers, and applications III / editors : Manijeh Razeghi; Alexei N. Baranov, Henry O. Everitt, John M. Zavada, Tariq Manzur. ISBN 9780819492135, p. 84960J(9 p.).

K. Jarašiūnas, P. Ščajev, S. Nargelas, R. Aleksiejūnas, J. Leach, T. Paskova, S. Okur, U. Ozgur, H. MorkoĆ§. Recombination and diffusion processes in polar and nonpolar bulk GaN investigated by time-resolved photoluminescence and nonlinear optical techniques // Proceedings of SPIE. 2012, vol. 8262 : Gallium Nitride Materials and Devices VII / editors: Jen-Inn Chyi, Yasushi Nanishi, Hadis MorkoĆ§, Joachim Piprek, Euijoon Yoon. ISBN 9780819489050. p. 82620G(10 p.).

L. Minkevičius, R. Suzanovičienė, G. Molis, A. Krotkus, S. Balakauskas, R. Venckevičius, I. Kašalynas, D. Seliuta, G. Valušis, V. Tamošiūnas. Solar cell imaging and characterization by terahertz techniques // Proceedings of SPIE. Bellingham : SPIE. 2012, vol. 8496 : Terahertz emitters, receivers, and applications III / editors : Manijeh Razeghi; Alexei N. Baranov, Henry O. Everitt, John M. Zavada, Tariq Manzur. ISBN 9780819492135, p. 849613(6 p.).

Patents

A. Žukauskas, P. Duchovskis, Z. Bliznikas, G. Samuolienė, A. Urbonavičiūtė, P. Vitta. Method and apparatus for the reduction of harmful nitrates in plants using radiant flux generated by a solid-state illuminator // European Patent No EP 2111097 B1, patvirtinimo data 20120523.

COOPERATION

University of Linkoping (Sweden)
CNRS Institute of Compound Materials at Bordeaux (France)
Institute Saclay Atomic Research Centre (France)
Institute of Industrial Science, Tokyo (Japan)
Ferdinand-Braun High Frequency Electronics Institute, Berlin (Germany)
Institute of Physics for Novel Materials, University of Lecce (Italy)
Interuniversity Microelectronic Centre IMEC (Belgium)
Rensselaer Polytechnic Institute, Troy, NY (USA)
Sensor Electronic Technology, Inc., Columbia, SC (USA)
University of South Carolina, Columbia, SC (USA)
National Institute of Standards and Technology, Washington, DC (USA)
High Pressure Research Centre (UNIPRESS), Warsaw (Poland)
Institute of Physics, Polish Academy of Sciences, Warsaw (Poland)
University of Nijmegen (The Netherlands)
National Taiwan University, Taipei (Taiwan)
Institute of Solid State Physics, University of Latvia (Latvia)
Institute for Single Crystals, Kharkov (Ukraine)
Kharkov University (Ukraine)
Lumilog Co (France)
“North Crystals” Company, Apatity (Russia)
RRC Kurchatov Istitute, Moscow (Russia)
Institute of Physics, Belarus Academy of Sciencies (Byelorussia)
Oslo University (Norway)
Institute of Physics (Lithuania)
Institute of Semiconductor Physics (Lithuania)

OTHER SCIENTIFIC ACTIVITIES

Prof. J. V. Vaitkus –

member of the Lithuanian Academy of Sciences, http://www.lma.lt.

Prof. A. Žukauskas –

member of the Lithuanian Academy of Sciences, http://www.lma.lt

Prof. E. Kuokštis –

member of the Research Council of Lithuania, http://www.lmt.lt/indexe.php.

DEPARTMENT OF RADIOPHYSICS

9 Saulėtekio, LT - 10222 Vilnius,
Tel. 236 6080, fax 236 6081
e-mail

Head - Prof. Habil. Dr. Jūras Banys

STAFF

Professors: Habil. Dr J. Banys, Habil. Dr. V. Ivaška, Habil. Dr. A. F. Orliukas, Habil. Dr. V. Palenskis, Habil. Dr. D. Čiplys, Habil. Dr. J. Matukas.
Docents: Dr. A. Brilingas, Dr. V. Kalesinskas, Dr. V. Samulionis, Dr. J. Vyšniauskas, Dr. A. Kežionis, Dr. Č. Pavasaris, Dr. R. Giriūnienė, Dr. V. Jonkus, Dr. R. Rimeika, Dr. V. Kunigėlis, Dr. M. Žilinskas, Dr. R. Sobiestijanskas, Dr. S. Pralgauskaitė, Dr. R. Grigalaitis, Dr. E. Kazakevičius, Dr. K. Svirskas.
Lectures: Dr. R. Aleksiejūnas, Dr. T. Šalkus, V. Adomaitis.
Research fellows: Dr. S. Lapinskas, Dr. V. Žalkauskas, Dr. A. Bernotas.
Engineering staff: A. Sereika, M. Ivanov. Dž. Jablonskas, S. Rudys, M. Juškauskas.
Doctoral students: A. Mikonis, B. Šaulys, Š. Bagdzevičius, M. Ivanov,
E. Palaimienė, V. Venckutė, S. Kazlauskas, P. Každailis.

RESEARCH INTERESTS

Investigation of technology conditions of the preparation and physical properties of some superionic ceramics
The preparation conditions of Li+ and conducted solid electrolyte ceramics and investigation peculiarities of the ionic transport in the frequency range from 1 Hz to 10 GHz in the temperature interval (300–1000)K. For preparation of conducted ceramic powder with different BET will be used. Investigation of the relationship between technological conditions of the preparation of the ceramics and their electrical properties. Investigation of the anode/electrolyte/cathode interfaces electrical properties.

Noise diagnostics of devices with quantum structures employed in telecommunication systems

During 2012 optical, electrical and noise characteristics of advanced nitride-based visible (also white) light emitting diodes (LEDs) with quantum structures, diode and transistor structures for terahertz (THz) detection have been investigated. The measurements have been performed in low frequency region (10 Hz–1 MHz). Investigation of operation and noise characteristics has been performed for initial samples and its changes during accelerated aging for some samples.
Noise characteristics of advanced high-power nitride-based light emitting diodes investigation during accelerated aging experiment have been carries out. The results show that degradation of the investigated diodes is determined by defect appearance in the active and adjacent regions. LED degradation manifests foremost by the optical and electrical noise intensity increasing and changes in cross-correlation between optical and electrical fluctuations. Detailed analysis shows that first of all active region, where light emission occurs, degrades during LED aging.
Investigation of the low frequency noise and responsivity characteristics of silicon CMOS transistor-based detectors for terahertz radiation under applied dc source-to-drain current has been carried out at room temperature. The results have shown that base noise of investigated transistors is thermal channel noise that is observed at higher frequencies and at lower frequencies generation-recombination and 1/f-type noise prevail thermal fluctuations.
Noise characteristics of bow-tie InGaAs diodes in forward and backward directions were measured in frequency range from 10 Hz to 1 MHz at room temperature. It was found that the spectral density of current fluctuations changes with frequency approximately as 1/f, indicating that origin of noise is superposition of generation and recombination processes in defects of the structure.
Low-frequency noise properties of beryllium delta-doped GaAs/AlAs quantum wells structures for THz emission and detection have been carried out over wide temperature range.

Management of engineering terms

Work on the Lithuanian-English Dictionary of Engineering. 20000 terms were managed in 2012.

RESEARCH PROJECTS CARRIED OUT IN 2012

Projects Supported by University Budget

Broad Band Dielectric Spectroscopy of Ferroelectrics and Related Materials. Prof. J. Banys. 2010–2013.

Investigation of Technology Conditions of the Preparation and Physical Properties of Some Superionic Ceramics. Prof. A. F. Orliukas. 2011–2015.

Acoustic Investigations of Promising Electronics, Telecommunications and Sensoric Materials. Prof. D. Čiplys. 2010–2012.

Noise Diagnostics of Devices with Quantum Structures Used in Telecommunication Systems. Prof. V. Palenskis. 2010–2015.

Management of Engineering Terms. Dr. V. Žalkauskas. 2007–2012.

Projects Supported by the Research Council of Lithuania

Dielectric and Ultrasonic Investigations of Composites of Inorganic Nanotubes and Polymers. Prof. J. Banys. 2012–2014.

COST Next Generation Cost Effective Phase Change Materials for Increased Energy Efficiency in Renewable Energy Systems in Buildings. Prof. J. Banys. 2008–2012.

COST Single- and Multiphase Ferroics and Multiferroics with Restricted Geometries (SIMUFER). Prof. J. Banys. 2009–2013.

Broadband Spectroscopy of Carbon Nanostructures and Ferroelectric Relaxors. Dr. J. Macutkevic 2012–2015.

COST Composites of Inorganic Nanotubes and Polymers (COINAPO ). Doc. V. Samulionis 2009–2013.

Creation of Physical Access Control Service System. High Technology Development Programme for 2011–2013. Project Participants: Vilnius University, Vilnius Gediminas Technical University, Nsoft. Doc. V. Jonkus.

Materials and Processing Development for Advanced Li Ion Batteries (No TAPLLT 03/2012). Prof. A. F. Orliukas.

Preparation and of the Ceramics with Fast Ionic Transport and Application for Functional Elements Solid State Ionics (Project Between France And Lithuania No TAPLL 06/2012). Prof. A. F. Orliukas.

Technological Processes of Membranes Production for Micro Solid Oxide Fuel Cells (No ATE-09/2012). Prof. A. F. Orliukas.

Research Council of Lithuania and Material Funds Taiwan-Latvia-Lithuania Cooperation Project Applications. Prof. A. F. Orliukas 2012.

International Science Programmes, Projects and Contracts

Investigation of Coexistence of Ferroelectric and Relaxor Ferroelectric States in TTB Structure Ceramics. Doc. R. Grigalaitis. 2011–2012

Nanostructured Lithium Conducting Materials “Puple” IRSES No.247579. Prof. A. F. Orliukas. 2011–2014.

EDA E-STAR project. Prof. J. Banys. 2010–2012.

MAIN PUBLICATIONS

Textbooks, Manuals

K. Maknys, G. Misevičius, V. Palenskis, S. Pralgauskaitė. Tikimybių teorijos ir atsitiktinių vyksmų uždaviniai : mokymo priemonė fizinių ir inžinerijos mokslų aukštųjų mokyklų studentams. Vilnius : Vilniaus universiteto leidykla, 2012. 100 p.

Other Books

A. Kaulakienė, J. Matukas, V. Palenskis, A. Petravičius, V. Valiukėnas, J. Vyšniauskas, G. Žalkauskaitė, V. Žalkauskas. Didysis anglų-lietuvių kalbų politechnikos žodynas [Elektroninis išteklius]. Vilnius : Juozas Vyšniauskas, 2012. [5000000 spaudos ženklų].

A. Kaulakienė, J. Vyšniauskas, G. Žalkauskaitė, V. Žalkauskas. Didysis lietuvių-anglų kalbų politechnikos žodynas [Elektroninis išteklius]. Vilnius : Juozas Vyšniauskas, 2012. [4000000 spaudos ženklų].

A. Kežionis, S. Kazlauskas, J. Krivochiža. Žemųjų dažnių mikrobangų elektromagnetinio lauko matavimai. Vilnius : Vilniaus universitetas, 2012. 88 p.

Articles

A. Bernotas, V. Šimonis. Effect of the Casimir energy on the bag model phenomenology of light hadrons // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 3, p. 181-192.

J. Vyšniauskas, V. Klimenko, J. Matukas, V. Palenskis. Simulation of electron diffusion effect on plasma formation in silicon TRAPATT diodes // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 3, p. 203-213.

S. Kazlauskas, A. Kežionis, T. Šalkus, A. Orliukas. Sintering of oxygen ion conductive ceramics and their electrical properties // Lithuanian Journal of Physics / Lithuanian Physical Society, Lithuanian Academy of Science. Vilnius : Lietuvos mokslų akademijos leidykla. 2012, Vol. 52, no. 3, p. 231-237.

J. Belovickis, R. Rimeika, D. Čiplys. Acousto-optic interaction with leaky surface acoustic waves in Y-cut LiTaO3 crystals // Ultrasonics. Amsterdam : Elsevier BV. 2012, Vol. 52, iss. 5, p. 593-597.

E. Kazakevičius, T. Šalkus, A. Kežionis, A. Selskis, A. Selskienė, V. Ponomaryov, . Suslikov, I. Studenyak. Electrical and dielectrical studies of Cu6PS5I1-xClx superionic composites // Solid state ionics. Amsterdam : Elsevier Science BV. 2012, Vol. 225 : Proceedings of the 18th International Conference on Solid State Ionics Warsaw, Poland, July 3 -8, 2011. p. 685-689.

R. Aleksiejūnas, V. Ivaška. Geometric phase decomposition in the basis of Hermite-Gaussian functions // Central European journal of physics. Warsaw : Versita. 2012, vol. 10, no. 1, p. 66-75.

T. Šalkus, M. Barre, A. Kežionis, E. Kazakevičius, O. Bohnke, A. Selskienė, A. Orliukas. Ionic conductivity of Li1.3Al0.3-xScxTi1.7(PO4)3 (x = 0, 0.1, 0.15, 0.2, 0.3) solid electrolytes prepared by Pechini process // Solid state ionics. Amsterdam : Elsevier Science BV. 2012, Vol. 225 : Proceedings of the 18th International Conference on Solid State Ionics Warsaw, Poland, July 3 -8, 2011. p. 615-619.

R. Rimeika, J. Belovickis, D. Čiplys. Leaky-surface-wave generated acoustic beam displacement upon reflection in lithium tantalate crystals // Applied physics letters. Melville: American Institute of Physics. 2013, vol. 102, iss. 1, Art. no. 031601 (4 p.).

R. Sobiestijanskas, W. Peng, N. Lemee, M. Karkut, J. Banys, J. Holc, M. Kosec. Microwave dielectric dispersion in a multiferroic Pb(Fe1/2Nb1/2)O3 thin film // Applied physics letters. Melville: American Institute of Physics. 2012, vol. 100, iss. 12, p. Art. no 122904(4 p.).

I. Studenyak, Y. Neimet, C. Cserhati, S. Kokenyesi, E. Kazakevičius, T. Šalkus, A. Kežionis, A. Orliukas. Structural and electrical investigation of (Ag3AsS3) (x) (As2S3)(1-x) superionic glasses // Central European journal of physics. Warsaw : Versita. 2012, vol. 10, no. 1, p. 206-209.

A. Orliukas, T. Šalkus, A. Kežionis, A. Dindune, Z. Kanepe, J. Ronis, V. Venckutė, V. Kazlauskienė, J. Miškinis, A. Lukauskas. Structure and broadband impedance spectroscopy of Li1.3AlyYx-yTi1.7(PO4)3 (x = 0.3; y = 0.1, 0.2) solid electrolyte ceramics // Solid state ionics. Amsterdam : Elsevier Science BV. 2012, Vol. 225 : Proceedings of the 18th International Conference on Solid State Ionics Warsaw, Poland, July 3 -8, 2011. p. 620-625.

V. Chivukula, D. Čiplys, J. Kim, R. Rimeika, J. Xu, M. Shur. Surface Acoustic Wave Response to Optical Absorption by Graphene Composite Film // IEEE transactions on ultrasonics ferroelectrics and frequency control. New York : IEEE. 2012, vol. 59, iss. 2, p. 265-270.

V. Samulionis, J. Banys, Y. Vysochanskii. Ultrasonic Relaxation in Phase Transition Region in Ferroelectric Semiconductors of Sn2P2S6 Family // Solid State Phenomena. Zurich : Scitec Publications Ltd. 2012, vol. 184 : Internal Friction and Mechanical Spectroscopy. p. 345-350.

J. Banys, D. Čiplys. 19th International Congress on Sound and Vibration (ICSV 19) // International Journal of Acoustics and Vibration. Auburn : International Institute of Acoustics and Vibration. 2012, Vol. 17. no. 2, p. 58.

A. Orliukas, O. Bohnke, A. Kežionis, S. Kazlauskas, V. Venckutė, D. Petrulionis, T. Žukauskas, T. Šalkus, A. Dindune, Z. Kanepe, J. Ronis, V. Kunigėlis. Broadband impedance spectroscopy of some Li+ and Vo** conducting solid electrolytes // Advanced electromagnetics. Paris : Advanced electromagnetics. 2012, vol. 1, no 1, p. 70-75.

I. Studenyak, Y. Neimet, A. Orliukas, A. Kežionis, E. Kazakevičius, T. Šalkus. Doslidžennia impedansu ta električnoi providnosti v superionnich steklach sistemi (Ag3AsS3)Ch(As2S3)1-Ch // Naukovij visnik Užgorodskogo universitetu. Seria Fizika = Uzhhorod University Scijentific Herald. Serijes Physics. Užgorod. 2012, T. 31. p. 49-54.

J. Vyšniauskas, T. Vasiliauskas, E. Šermukšnis, V. Palenskis, J. Matukas. Investigation of high-speed transient processes and parameter extraction of InGaAsP laser diodes // Semiconductor laser diode technology and applications. Rijeka : InTech, 2012, p. 161-180.

S. Pralgauskaitė, V. Palenskis, J. Matukas. Low frequency noise characteristics of multimode and singlemode laser diodes // Semiconductor laser diode technology and applications. Rijeka : InTech, 2012, p. 133-160.

Materials of conferences

J. Belovickis, R. Rimeika, D. Čiplys. Reflection of leaky acoustic wave from metalized surface of piezoelectric crystal // ICSV 19 : Proceedings of the 19th International Congress of Sound and Vibration, Vilnius, Lithuania, July 8-12, 2012 [CD]. Vilnius : Vilniaus universiteto leidykla, 2012, [p.1-6].

J. Belovickis, R. Rimeika, D. Čiplys. Acousto-optic interaction of leaky surface acoustic waves in Y-cut LiTaO3 crystals // International congress on ultrasonics, Gdansk 2011. Book series : AIP Conference Proceedings. Vol. 1433. ISSN 0094-243X. Melville : American Institute of Physics, 2012, p. 68-71.

L. Minkevičius, M. Ragauskas, J. Matukas, V. Palenskis, S. Pralgauskaitė, D. Seliuta, I. Kašalynas, G. Valušis. InGaAs bow-tie diodes for terahertz imaging: low frequency noise characterisation // Proceedings of SPIE. Bellingham : SPIE. 2012, vol. 8496 : Terahertz emitters, receivers, and applications III / editors : Manijeh Razeghi; Alexei N. Baranov, Henry O. Everitt, John M. Zavada, Tariq Manzur. ISBN 9780819492135, p. 84271X(9 p.).

S. Pralgauskaitė, J. Matukas, J. Vyšniauskas, V. Kornijčuk, V. Palenskis, L. Minkevičius, G. Valušis, A. Lisauskas, S. Boppel, V. Krozer, H. Roskos. Low freguency noise characterisation of biased silicon CMOS terahertz detectors // MIKON 2012: 19th international conference on microwaves, radar and wireless communications : IEEE proceedings, Poland, May 21-23. Warsaw, 2012, p. 631-633.

COOPERATION

Institute of Semiconductor Physics (Lithuania)
Institute of Solid State Physics (Latvia)
Institute of Physics Czech Academy of Sciences (Czech Republic)
Uzhgorod University (Ukraine)
Cambridge University (UK)
Paris University (France)
Duisburg University (Germany)
Bucharest University (Romania)
Josef Stefan Institute (Slovenia)
Aveiro University (Portugal)
Vancouver University (Canada)
Belfast University (UK)
Wroclaw University (Poland)
Leipzig University (Germany)
Rensselaer Polytechnic Institute (USA)
Institute of Semiconductor Physics (Lithuania)
Centre National de la Recherche Scientifique Laborataire des Oxydes et Fluorures University du Maine (France)
V.I. Vernadski Institute of General and Inorganic Chemistry NAS of Ukraine (Ukraine)
Cosejo Superior de Investigationes Centificas (Spain)
Universidad Carlos 3 de Madrid (Spain)
Institute of Inorganic Chemistry Riga Technical University (Latvia)
ETH Zuerich (Schweiz)
EMPA Schweiz
Rensselaer Polytechnic Institute, Troy, New York (USA).

OTHER SCIENTIFIC ACTIVITIES

Prof. J. Banys –

member of program committee FM&NT;
member of international advisory board of RCBJSF;
member of international advisory board of EMF;
member of council of AMPERE group;
member of international advisory board ECAPD.

Prof. A. F. Orliukas –

member of International Advisory Board of 18th international conference on Solid State Ionics;
member of International Advisory Board of international symposium on Systems with Fast Ionic Transport.

Dr. D. Čiplys –

editorial board member of the Ultragarsas (Ultrasound Journal), http://www.ktu.lt/ultra/ultra2.asp?file=journal/editor).

Doc. R. Giriūnienė –

member of BASNET (Baltic States Network: women in sciences and high technology, www.basnetforumas.eu).

Prof. V. Palenskis –

member of Technical Committee No 37 “Terminology” of the Lithuanian Standardization Department, and the head of subcommittee “Engineering and Electronics”;
member of Technical Committee No 66 “Non-destructive Testing” of the Lithuanian Standardization Department;
member of Technical Committee No 69 “Applications of Statistical Methods” of the Lithuanian Standardization Department.

DEPARTMENT OF THEORETICAL PHYSICS

9 Saulėtekio, LT-10222 Vilnius
Tel. 236 6030, fax 236 6003
E-mail:

Head – Prof. Habil. Dr. Leonas Valkūnas

STAFF

Professors: Habil. Dr. L. Valkūnas (part-time), Habil. Dr K. Pyragas (part-time), Dr. D. Abramavičius, Dr. E. Anisimovas.
Docents: Dr. J. Bučinskas, Dr. J. Šulskus, Dr. K. Glemža, Dr. T. Gajdosik, Dr. G.Trinkūnas.
Lectures: Dr. O. Rancova, Dr. M. Mačernis.
Doctoral students: V. Balevičius, V. Butkus, J. Chmeliov, J. Meldaikis, S. Toliautas, S. Malickaja.

Process Modelling Laboratory at the Department of Theoretical Physics

Head – Dr. Mindaugas Mačernis.

RESEARCH INTERESTS

Development of exciton theory and its application to the nonlinear spectroscopy of molecular complexes
Excitation dynamics in complex molecular systems and nanostructures
Coherent control and optimization of nonlinear optical signals of bio molecules and nano-systems
Development of the theoretical background of multi-dimensional spectra of molecular complexes
Modelling of single molecular spectra of complex systems
Development of quantum mechanics and quantum electrodynamics for characterization of transitions in atoms, molecules and molecular complexes
Application of high performance parallel computing in theoretical modelling of processes photoactive organic materials and nanosystems

RESEARCH PROJECTS CARRIED OUT IN 2011

Project Supported by University Budget

Modelling of Processes in Photoactive Organic Materials and Nanosystems. Prof. L. Valkūnas. 2011–2018.

Theoretical modelling scheme describing the excitation dynamics and relaxation in a molecular aggregate interacting with the thermal bath has been developed. On the basis of this theoretical scheme evolution of two-dimensional photon-echo (2D PE) spectrum of various molecular aggregates was theoretically considered. Quantum beats in two-dimensional spectroscopy traditionally are associated with electronic phenomena of excitonic systems and the nuclear degrees of freedom are included as a general dephasing. However, molecular systems are coupled to various damped high-frequency modes of molecular vibrations, which also lead to the spectral beats. Various models of vibronic bath were discussed in context of two-dimensional electronic spectroscopy. The limits of damped, undamped and overdamped molecular vibrations were analyzed in detail and their effects were described. The method for the separation of vibrational and electronic wave packet motion was also used to demonstrate the possibility to discriminate between the possible input of the vibrational coherence from the electronic coherence.
The exciton dynamics in a molecular heterodimer was studied as a function of differences in excitation and reorganization energies, asymmetry in transition dipole moments and excited state lifetimes. The heterodimer is usually composed of two molecules modelled as two-level systems coupled by the resonance interaction. The system-bath coupling was taken into account as a modulating factor of the energy gap of the molecular excitation, while the relaxation to the ground state was treated phenomenologically. Comparison of the description of the excitation dynamics modelled using either the Redfield equations (secular and full forms) or the Hierarchical quantum master equation (HQME) was demonstrated. Possible role of the dimer as an excitation quenching centre in photosynthesis self-regulation was also demonstrated. It was concluded that the system-bath interaction rather than the excitonic effect determines the excitation quenching ability of such a dimer.
Photo-protective non-photochemical quenching (NPQ) in higher plants is the result of the formation of energy quenching traps in the light-harvesting antenna of photosystem II (PSII). It has been proposed that this quenching trap is a lutein molecule closely associated with the chlorophyll terminal emitter of the major light-harvesting complex LHCII. A combination of time-dependent density functional theory (TD-DFT) and the semi-empirical MNDO-CAS-CI method to model the chlorophyll-lutein energy transfer dynamics of the highly-quenched crystal structure of LHCII was analyzed in the term of possible role in NPQ. Calculations revealed that the incoherent ‘hopping’ of energy from Chla612 to the short-lived, dipole forbidden 21Ag- state of lutein620 accounts for the strong fluorescence quenching observed in these crystals. This adds weight to the argument that the same dissipative pathway is responsible for in vivo NPQ.
Recent time-resolved studies revealed the switching behaviour of single LHCII trimer. The diffusion-controlled model describing the essential protein dynamics underlying this switching is formulated. The calculated blinking statistics is comparable with experimental results, and not only reproduce the power-law behaviour at intermediate times, but also follow the experimentally observed deviations from such behaviour at shorter time scale. These results enable us to propose that the coupling of fast protein dynamics to a specific slow coordinate is at the basis of the regulatory switching in the NPQ conditions.
Aggregation of the major light-harvesting complexes LHCII in vitro is associated with similar quenching as is the case in the NPQ conditions. Although aggregates present a useful model system, the analysis of their time-resolved data is complicated by the uncertainty and heterogeneity of their size. Recently NPQ has been induced in vitro also in isolated, non-aggregated LHCII complexes. We used this new quenching model to study the dynamics of excitation energy migration in quenched state unaffected by aggregation. In concert with the state of the art modelling the obtained dependency of the decay times of chlorophyll electronic excitations depending on sample conditions allowed us to conclude that LHCII is an extremely adaptable biological macromolecule capable of adjusting its structural and spectral properties to the varying environmental conditions.
The variability of the exciton spectra of bacteriochlorophyll molecules in light-harvesting (LH) complexes of photosynthetic bacteria ensures the excitation energy funnelling trend towards the reaction centre. The decisive shift of the energies is achieved due to exciton spectra formation caused by the resonance interaction between the pigments. The possibility to resolve the upper Davydov sub-band corresponding to the B850 ring and, thus, to estimate the exciton bandwidth by analyzing the temperature dependence of the steady-state absorption spectra of the LH2 complexes is demonstrated. For this purpose a self-modelling curve resolution approach was applied for the analysis of the temperature dependence of the absorption spectra of LH2 complexes from the photosynthetic bacteria Rhodobacter sphaeroides and Rhodoblastus acidophilus. Estimations of the intradimer resonance interaction values as follows directly from obtained estimations of the exciton bandwidths at room temperature give 385 and 397 cm−1 for the LH2 complexes from the photosynthetic bacteria Rhodobacter sphaeroides and Rhodoblastus acidophilus, respectively. At 4 K the corresponding couplings are slightly higher (391 and 435 cm−1, respectively). The retained exciton bandwidth at physiological conditions supports the decisive role of the exciton coherence determining the light absorption in bacterial light-harvesting antenna complexes.
The possibility of affecting optical spectra and the quantum yield of the energy transfer in the LH2 complexes at the presence of the metal nanoparticles or nanoshels is considered. Increasing intensity of the excitonic transitions in the LH2 complexes due to the borrowing of the oscillator strength from the surface plasmons from the metal nanoparticle and nanoshell was predicted. While both absorption and quenching of the excitations increase in the vicinity of the metal nanoparticle, having opposite effects, the total yield of excitation transfer to the reaction centres is shown to grow in a certain rage of parameters.
The problem of energy and charge transfer in molecular assemblies still raises a lot of questions as it is the intermediate neither coherent nor pure probabilistic process. The quantum probabilistic process has been studied using the stochastic Schrödinger equation approach. This application required several steps to be accomplished. The first is to develop the algorithm to generate a stochastic trajectory from a predefined noise correlation function. The second step is to develop a stochastic propagator. Both these steps have been implemented into the computer program. The energy transfer inside the photosynthetic pigment-protein Fenna-Matthews-Olson aggregate has been simulated. It has been fond that the exciton travels through the aggregate much faster than predicted from the rate equations. However, the capture of the excitation or collapse of the wave function happens on a slower timescale.
Molecular electronic structure of ground and excited states of a photochromic indolo[2,1b][1,3]benzoxazine molecule incorporating closed ring system which opens upon UV light excitation, was studied using various quantum chemical methods. Three local minima of the ground electronic state potential energy surface and related transition states were identified along the path of rotation of 4‑nitrophenol group. The evaluated transition energy barriers between local minima nearest to the initial structure of investigated molecule are less than 2 kBT, making open structures likely to revert to the initial structure by thermalization. Results obtained using ab initio GMC‑QDPT method were explored in detail and compared to the widely used TDDFT and semi-empiric ZINDO, as well as ab initio GUGA-CI methods.
The effect of homogeneous high-frequency stimulation (HFS) on a one-dimensional chain of coupled excitable elements governed by the Fitz-Hugh-Nagumo equations has been investigated. The high-frequency term has been eliminated by the method of averaging and shown that the averaged dynamics depends on the parameter A = a/ω equal to the ratio of the amplitude a to the frequency ω of the stimulating signal, so that for large frequencies an appreciable effect from the HFS is attained only at sufficiently large amplitudes. The averaged equations have been analyzed by an asymptotic theory based on the different time scales of the recovery and excitable variables. As a result, we have obtained the main characteristics of a propagating pulse as functions of the parameter A and derived an analytical criterion for the propagation failure. We have shown that depending on the parameter A, the HFS can either enhance or suppress pulse propagation and revealed the mechanism underlying these effects. The theoretical results have been confirmed by numerical simulations of the original system with and without noise.
A detailed analysis of dimensional structural transitions in small Yukawa clusters and their temporal evolution was carried out. We showed that even in the most primitive systems composed of only a few strongly interacting particles, the order parameter exhibits a power-law behaviour in the vicinity of the critical point of the continuous transition. The distribution of topological and geometrical defects in two-dimensional Coulomb clusters was studied using the molecular dynamics. The size, structure and distribution of geometry-induced lattice imperfections strongly depend on the system size and the energetic state. Proliferation of defects in metastable configurations destroys the orientational order of the Wigner lattice.
In the context of the see-saw mechanism the one-loop radiative corrections to the mass parameters which produce mass terms for the neutral leptons has been calculated. Numerical analysis of the possible effect caused by light neutrino masses as functions of the heavy neutrino masses and the parameters entering the description of the see-saw mechanism and the spontaneous symmetry breaking of the Standard Model gauge group has been fulfilled.
For the boundary problem of electromagnetic wave scattering by set of spheres the expressions for reradiated wave fields using Debye potentials and spherical wave addition formulae were derived.

The public access to Vilnius Universities supercomputer from the High Performance Computing Center (HPCC) of the Lithuanian National Centre for Physical Sciences and Technology (NCPST) is administrated by Process Modelling Laboratory at the Department of Theoretical Physics and is used for research work (http://supercomputing.ff.vu.lt).

MAIN PUBLICATIONS

Monographs, Studies

M. Mačernis. Environmental Effects on Photoinduced Processes in Organic Molecules: Schiff base, Bacteriorhodopsin, Carotenoids : [monografija]. Saarbrucken : Lambert Academic Publishing, 2011. 168 p. [vėluojanti].

Textbooks, Manuals

M. Mačernis. Objektinis programavimas : teorija, Java, Android. Vilnius, 2012. 308 p.

Articles

V. Novičenko, K. Pyragas. Computation of phase response curves via a direct method adapted to infinitesimal perturbations // Nonlinear dynamics. Dordrech : Springer Netherlands. 2012,vol. 67, no 1, p. 517-526.

E. Anisimovas, A. Radzvilavičius. Configurational Entropy of Confined Yukawa Clusters // Contributions to Plasma Physics. Weinheim : Wiley - VCH Verlag GmbH & Co. KGaA. 2012, Vol. 52, iss. 3, p. 170-173.

A. Radzvilavičius, O. Rancova, E. Anisimovas. Dimensional transitions in small Yukawa clusters // Physical review. E : statistical physics, plasmas, fluids, and related interdisciplinary topics. College Park : American Physical Society. 2012, vol. 86, no. 1, art. no. 016404(8 p.).

I. Goliney, V. Sugakov, L. Valkūnas, G. Vertsimakha. Effect of metal nanoparticles on energy spectra and optical properties of peripheral light-harvesting LH2 complexes from photosynthetic bacteria // Chemical physics. Amsterdam : Elsevier Science. 2012, Vol. 404, p. 116-122.

L. Valkūnas. Electronic processes in organic systems // Chemical physics. Amsterdam : Elsevier Science. 2012, Vol. 404, p. 1.

M. Mačernis, J. Šulskus, C. Duffy, A. Ruban, L. Valkūnas. Electronic Spectra of Structurally Deformed Lutein // The journal of physical chemistry A. Washington : American Chemical Society. 2012, Vol. 116, iss. 40, p. 9843-9853.

V. Balevičius, A. Gelžinis, D. Abramavičius, T. Mančal, L. Valkūnas. Excitation dynamics and relaxation in a molecular heterodimer // Chemical physics. Amsterdam : Elsevier Science. 2012, Vol. 404, p. 94-102.

D. Rutkauskas, J. Chmeliov, M. Johnson, A. Ruban, L. Valkūnas. Exciton annihilation as a probe of the light-harvesting antenna transition into the photoprotective mode // Chemical physics. Amsterdam : Elsevier Science. 2012, vol. 404, p. 123-128.

L. Valkūnas, J. Chmeliov, T. Kruger, C. Ilioaia. How photosynthetic proteins switch // Journal of physical chemistry letters. Washington: American Chemical Society, p. 2779-2784.

O. Rancova, J. Šulskus, D. Abramavičius. Insight into the structure of photosynthetic LH2 aggregate from spectroscopy simulations // The journal of physical chemistry B. Washington : American Chemical Society. 2012, vol. 116, iss. 27, p. 7803-7814.

L. Nickelson, J. Bučinskas. Microwave power absorbed by and scattered from a multilayered zero-index anisotropic metamaterial-semiconductor cylinder // Applied physics. A. Materials science & processing. Heidelberg : Springer. 2012, Vol. 109, no 4, p. 883-889.

V. Butkus, L. Valkūnas, D. Abramavičius. Molecular vibrations-induced quantum beats in two-dimensional electronic spectroscopy // Journal of chemical physics. Melville : American Institute of Physics. 2012, vol. 137, no. 4, Art. No. 044513.

I. Ratas, K. Pyragas. Pulse propagation and failure in the discrete FitzHugh-Nagumo model subject to high-frequency stimulation // Physical review. E : statistical physics, plasmas, fluids, and related interdisciplinary topics. College Park : American Physical Society. 2012, vol. 86, no. 4, Art. no. 046211(9 p.).

V. Butkus, D. Zigmantas, L. Valkūnas, D. Abramavičius. Vibrational vs. electronic coherences in 2D spectrum of molecular systems // Chemical physics letters. Amsterdam : Elsevier Science BV. 2012, vol. 545, no. 1, p. 40-43.

D. Abramavičius, A. Nemeth, F. Milota, J. Sperling, S. Mukamel, H. Kauffmann. Weak Exciton Scattering in Molecular Nanotubes Revealed by Double-Quantum Two-Dimensional Electronic Spectroscopy // Physical review letters. College Park : American Physical Society. 2012, vol. 108, no. 6, art. no 067401(5 p.).

Materials of conferences

L. Nickelson, J. Bučinskas. Microwave scattered and absorbed powers by a multilayered zero-index anisotropic metamaterial-semiconductor cylinder // Meta'12 : 3rd International conference on metamaterials, photonic crystals and plasmonics : proceedings, 19-22, 2012. Paris, France / edited by Said Zouhdi, Xavier Begaud. Paris, 2012, p. 53-58.

COOPERATION

Institute of Physics (Lithuania)
Institute of Theoretical Physics and Astronomy (Lithuania)
University of California, Berkeley, and University of California, Irvine (USA)
Institute of Physics of Charles University (Czech Republic)
Institute of Solid State Physics, University of Latvia (Latvia)
Riga Technical University (Latvia)
Free University of Amsterdam (Netherlands)
Free University of Brussels (Belgium)
Lund University (Sweden)
Nuclear Research Centre, Saclay (France)
State key laboratory of supramolecular structure and materials, Jilin University (China)
Dalian Institute of Chemical Physics, Chinese Academy of Sciences (China)
University of Antwerp (Belgium)

OTHER SCIENTIFIC ACTIVITIES

Prof. L. Valkūnas, http://www.tfk.ff.vu.lt/~valk/lt/ -

member of the Lithuanian Academy of Sciences;
winner of the National Prize for Science;
winner of the A. Jucys prize of the Lithuanian Academy of Sciences;
member of the expert commissions of ESF and of the Lithuanian Research Council;
head of the Laboratory of Molecular Compound Physics in the Institute of Physics of the Centre for Physical Sciences and Technology;
deputy director of the Centre of Physical Sciences and Technology;
vice-president of the Lithuanian Physical Society;
editorial board member of the Lithuanian Journal of Physics;
member of the committee for studies of Computational Physics at Vilnius University;
permanent referee of the Phys. Rev. Lett., Phys. Rev. B, Biophys. J., J. Phys. Chem., Chem. Phys., and other journals.

Prof. K. Pyragas, http://pyragas.pfi.lt/ –

head of the laboratory of the Nonlinear Dynamics and Nanophysics in the Semiconductor Physics Institute, Centre for Physical Sciences and Technology;
editorial board member of the journal International Journal of Bifurcation and Chaos (IJBC) in Applied Sciences and Engineering
editorial board member of the journal International Review of Physics (IREPHY);
editorial board member of the journal Chaos & Complexity Letters, International Journal of Dynamical Systems Research;
editorial board member of the journal Nonlinear Phenomena in Complex Systems, An Interdisciplinary Journal;
editorial board member of the journal Nonlinear Analysis Modelling and Control;
permanent referee of the Physical Review Letters, Physical Review E, Physica D, Physics Letters A, and other journals;
board member of the International Physics and Control Society (IPACS);
board member of the Lithuanian Association of Nonlinear Analysis (LANA).

Prof. E. Anisimovas –

referee of the Physical Review Letters, Physical Review B, Physica E, and other journals.

Doc. K. Glemža –

committee member for the studies of Physics at Vilnius University.

Doc. J. Šulskus –

chairman of the committee for studies of Computational Physics at Vilnius University.