The Photoactivity Department was founded in 1966 year by Professor, Member of the National Academy of Sciences of Ukraine Marat Terentijovych Shpak (1926-1993). The Department was headed by Professor, Doctor of Science in physics and mathematics Galyna Oleksandrivna Puchkovska from 1993 to 2010. In 2006, on the basis of the photoactivity department 2 new departments were created - Department of Coherent and Quantum Optics (headed by Corresponding Member of the National Academy of Sciences of Ukraine Leonid Yatsenko) and the Department of Laser Spectroscopy (headed by Corresponding Member of the National
Academy of Sciences of Ukraine Anatoliy Negrijko). Since 2010 the Photoactivity Department is headed by Doctor of Science in physics and mathematics Mykhailo Bondar.
Basic directions of scientific activity: complex investigations of the molecular systems – broad-range optical properties, phase transitions in and the structure of molecular crystals, spectroscopy of organic disordered media, composite materials with inorganic nanoparticles and metal oxides; experimental and theoretical investigations of the charge-carrier transport and trapping in disordered organic semiconductors and nanocomposite materials; multi-photon spectroscopy of large organic molecules for manifold nonlinear optical applications (two-photon fluorescence microscopy, optical limiting, 3D optical data storage, two-photon photodynamic therapy, and STED applications); lasing phenomena in dye-doped cholesteric liquid crystals.
Main facilities and experimental methods: ІR-Fourier, Raman, and UV-spectroscopy, thermally stimulated fluorescence equipment, steady-state and timeresolved spectral measurements, nonlinear optical measurements (open aperture z-scan technique, pump-probe transient absorption methods).
- Lenin Komsomol Prize – 1972 р. (М. V. Danyleiko).
- Republican Komsomol M. Ostrovsky Prize – 1976 р. (V. І. Romanenko).
- State Prize of Ukraine in Science and Technology – 1974 р. (М. Т. Shpak, Ye. О. Tikhonov), 1984 р. (G. О. Puchkovska), 1986 р. (М. Т. Shpak), 1998 р. (М. V. Danyleiko, А. М. Negrijko, Ye. О. Tikhonov, L. P. Yatsenko).
- Prykhot’ko Prize 2002 р (N. І. Ostapenko), 2006 р. (G. О. Puchkovska, V. І. Melnyk).
The most important achievements:
- The correlation between thermal, spectroscopic, luminescence and acoustic properties of the benzophenone glass phase was revealed and its nanoscale clustering structure was shown (V. І. Melnyk, К. І. Nelypovich, in collaboration with N. O. Davydova).
- The low-temperature fractional thermally-stimulated-luminescence (TSL) method was developed for investigations of the charge trapping and probing the density-of-states distribution in disordered organic semiconductors. (А. К. Кadashchuk, Yu. А. Skrishevsky, О. Yu. Vakhnin, І. І. Fishchuk).
- The discrete nature of the charge-carrier traps energy spectra and dispersion of the frequency factor in silicon organic polymer films were shown based on the modified TSL method (N. І. Ostapenko, А. F. Gumenjuk, О. О. Kerita).
- Two-photon stimulated emission transitions (STED) were experimentally observed in organic molecules for the first time and corresponding STED spectra were obtained using time-resolved femtosecond spectroscopy (М. V. Bondar, О. V. Przhonska).
- The first laser on dye-doped cholesteric liquid crystals was created (І. P. Ilchishun, Ye. О. Тikhonov, V. G, Тіshchenko, М. Т. Shpak).
A correlation between the luminescence properties of the composite liquid crystal (LC) 5CB – carbon nanotubes (CNT) was revealed on the basis of its thermodynamic characteristics received using the Differential Scanning Calorimetry method and conductivity measurements. The obtained experimental data show that the observed peculiarities in the luminescence spectra of pure and doped LC 5CB are due to the phase transformations of the crystal and conformation change of the molecule 5CB.
The multiplet structure of the luminescence spectra of doped benzophenone and naphthalene crystals was analyzed on the basis of the symmetry properties of their free molecules and crystals. It was found that the examined fluorescence and phosphorescence spectra have a doublet character.
A correlation between the thermal, spectroscopic, luminescence and acoustic properties of the benzophenone glass phase was revealed, and its nanoscale clustering structure was shown (V. Melnyk, M. Curmei, G. Klishevich).
A new model of thermally stimulated luminescence (TSL) in disordered organic semiconductors based on the Gaussian disorder concept was suggested and experimentally verified for a great variety of conjugated polymers and oligomers, which pioneered the use of the TSL method for probing the density-ofstate distribution.
A unified analytic model of hopping charge transport in disordered organic semiconductors including both energetic disorder and polaronic contributions at high carrier concentrations was developed for the first time (А. Кadashchuk, Yu. А. Skryshevsky, О. Vakhnin, І. І. Fishchuk).
Self-organization processes in silicon-organic polymer films of poly(di-n-hexylsilane) were investigated by optical spectroscopy methods and the formation of two liquid crystal phases in the polymer annealed at temperature above the phase transition was shown for the first time (N. І. Ostapenko, А. F. Gumenjuk, О. О. Kerita).
Two-photon stimulated emission transitions (STEDs) were experimentally observed in organic molecules for the first time and the corresponding STED spectra were obtained using time-resolved femtosecond spectroscopy (М. V. Bondar, О. V. Przhonska).
The formation and the stability of various polymorphic phases (rotator crystals or liquid crystal phases) of long-chain amphiphilic mollecules (n-paraffins, carboxylic acids, mixtures of surfactants of with opposite charges) were evaluated and found to depend on the alkyl chain length, terminal group chemistry, molecular packing constraints and electrostatic effects. A strongly enhanced stability of catanionic complexes in comparison with that of pure materials (of some 50 K) was found, which represents a great opportunity for the exploitation of those complexes in a variety of applications such as lubrication and detergency (T. Gavrilko, I. Gnatyuk).
The first laser on dye-doped cholesteric liquid crystals was created (І. P. Ilchishin, Ye. О. Тikhonov, V. G, Тіshchenko, М. Т. Shpak).
- Ye. O. Tikhonov, M. T. Shpak. Non-linear Phenomena in Organic Compounds (1979) (in Russian);
- L. M. Babkov, G. O. Puchkovska, S. P. Makarenko, T. A. Gavrilko. Infrared Spectroscopy of H-bonded Crystals (Kyiv, Naukova Dumka, 1989) (in Russian);
- N. I. Ostapenko, V. I. Sugakov, M. T. Shpak. Spectroscopy of Defects in Molecular Crystals (1988) (in Russian);
- N. I. Ostapenko, V. I. Sugakov, M. T. Shpak. Spectroscopy of Defects in Organic Crystals (1993).
- M. V. Danyleiko, L. P. Yatsenko. Resonance Phenomena in Ring Gas Lasers (1994) (in Russian);
- Semiconducting Polymers: Chemistry, Physics and Engineering, Vol I. Second Edition, Eds. G. Hadziioannou and G. G. Malliaras, (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim), (2007); Chapter 8, by V. I. Arkhipov, I. I. Fishchuk, A. Kadashchuk, H. Bassler. Charge transport in pristine and doped random organic semiconductors, pp. 275-383.
- Photophysics of Molecular Materials: From Single Molecules to Single crystals, Ed. G. Lanzani, (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim), (2006); Chapter 6, by V. I. Arkhipov, I. I. Fishchuk, A. Kadashchuk, H. Bassler. Charge Transport in Disordered Organic Semiconductors, pp. 261-366.
- I. I. Fishchuk, A. Kadashchuk. Effective Medium Approximation Theory Description of Charge-Carrier Transport in Organic Field-Effect Transistors, Chapter 7 in Small Organic Molecules on Surfaces: Fundamentals and Applications, Springer Series in Material Science 173, Eds. H. Sitter, C. Ambrosch-Draxl, M. Ramsey, (Springer-Verlag Berlin Heidelberg) (2013), pp. 171-201.
- V. I. Arkhipov, I. I. Fishchuk, A. Kadashchuk, H. Bassler. Charge transport in pristine and doped random organic semiconductors. Chapter 8 in Semiconducting Polymers: Chemistry, Physics and Engineering, Vol I. 2nd Edition, Eds. G. Hadziioannou and G. G. Malliaras, (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) (2007), pp. 275-383.
- V. I. Arkhipov, I. I. Fishchuk, A. Kadashchuk, H. Bassler. Charge Transport in Disordered Organic Semiconductors, Chapter 6 in Photophysics of Molecular Materials: From Single Molecules to Single crystals, Ed. G. Lanzani, (Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim), (2006), pp. 261-366.
- K. D. Belfield, S. Yao, M. V. Bondar. Two-photon absorbing photonic materials: from fundamentals to applications. Advances in Polymer Science, (2008), 213 (Photoresponsive Polymers I), pp. 97-156.
- O. V. Przhonska, S. Webster, L. A. Padilha, H. Hu, A. D. Kachkovski, D. J. Hagan, E. W. Van Stryland. In Advanced Fluorescence Reporters in Chemistry and Biology I: Fundamentals and Molecular Design, Springer Series in Fluorescence; A. P. Demchenko, Ed.; Springer-Verlag: Berlin Heidelberg, (2010).
- K. D. Belfield, S. Yao, M. V. Bondar. Organic multiphoton absorbing materials and devices. Optical Science and Engineering, (2008), 133 (Introduction to Organic Electronic and Optoelectronic Materials and Devices), pp. 573-606.
- V. I. Melnyk, N. A. Davydova, K. I. Nelipovich, J. Baran, J. I. Kukielski. Heterogeneous structure of glassy benzophenone. Phys. Rev. B, 2002, 65, 094201/1–3. X. Li, A. Kadashchuk, I. I. Fishchuk, W. T. T. Smaal, G. Gelinck, D. J. Broer, J. Genoe, P. Heremans and H. Bassler. Electric Field Confinement Effect on Charge Transport in Organic Field-Effect Transistors. Phys. Rev. Let., 2012, 108, 066601.
- K. D. Belfield, M. V. Bondar, A. R. Morales, X. Yue, G. Luchita, O. V. Przhonska, O. D. Kachkovsky. Two-photon absorption and time-resolved stimulated emission depletion spectroscopy of a newfluorenyl derivative. ChemPhysChem, 2012, 13(15), 3481.
- A. Gumenjuk, N. Ostapenko, Yu. Ostapenko, O. Kerita, S. Suto, A. Watanabe. Oscillatory regularity of charge carrier traps energy spectra in silicon organic polymer poly(di-n-hexylsilane). Low Temperature Physics, 2012, 38, 932.
- T. V. Bezrodna, G. V. Klishevich, V. I. Melnyk, V. V. Nesprava, G. A. Puchkovska, I. T. Chashechnikova. Photoluminescence of montmorillonite clay minerals modified by cetyltrimethylammonium bromide. J. Appl. Spect., 2011, 77(6), 784.
- T. A. Gavrilko, V. I. Styopkin, T. V. Bezrodna, G. O. Puchkovska, J. Baran, M. Drozd. Molecular dynamics and phase behavior of binary mixtures of stearic acid and cetyltrimethylammonium bromide as studied via Davydov splitting of molecular vibrational modes. Ukr. J. Phys., 2013, 58(7), 637.
- L. Kernazhitsky, V. Shymanovska, T. Gavrilko, V. Naumov, V. Kshnyakin, T. Khalyavka. A comparative study of optical absorption and photocatalytic properties of nanocrystalline single-phase anatase and rutile TiO2 doped with transition metal cations. J. Solid State Chemistry, 2013, 98, 511.
- I. P. Ilchishin, Ye. A. Тikhonov, V. G. Тishchenko, М. Т. Shpak. Pisma v GETF, 1980, 32, 27 (in Russian).
N.I. Ostapenko explores the optical properties
of nanostructures silicon-organic polymers.
A.K. Kadaschuk for the measurement
of low-temperature thermoluminescence.
O. Przhonska and M.V. Bondar discuss
the effects of anisotropy of fluorescence of organic molecules.
V.I. Miller and T.V. Bezrodna survey by low-temperature
luminescence heterogeneous nanocomposites.
Collective photo of department
The most important publications of the research group of A. Kadashchuk can be found at the following link:
- CRDF № UKB2-2923-KV-07: “High Performance Fluorescent Probes for Multiphoton Fluorescence and FLIM Bioimaging”.
- People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme FP7/2007-2013/ “Nanochemistry of Molecular Materials for 2-Photon Functional Applications (Nano2Fun)” under REA grant agreement n°607721.