Time-resolved Raman probing technique is used to investigate the collisional relaxation of high-laying C-H vibrations in CHF₃ and CHF₂Cl molecules. The relaxation rates both in collisions with parent molecules and a number of buffer gases were measured. The rate values were found to be abnormally fast. The relaxation is faster than single collision in parent gas and requires a few (3 - 8) collisions for nonpolar gases. For polar gases the relaxation is still faster. The conclusion is made that observed ultrafast relaxation of C-H modes is caused by energy transfer from excited `bright' state to nearby `dark' ones. The theoretical model of this process along with the numerical estimations is presented.

The applicability of a computer simulation technique for investigating photoinduced dynamics of polyatomic molecules, based on a combination of classical dynamics and a quantum surface hopping algorithm is discussed. The Wigner representation of a molecule's time-dependent density matrix is calculated and the corresponding approximation of the molecule's dynamics as a series of quantum jumps between the electronic states with classical movement on single electronic levels between jumps is presented. The effectiveness of this approach in computer simulations of a molecule's photodissociation dynamics in the presence of a strong laser field is shown and computer simulation results on IR photostimulated dissociation in HCl⁺ molecule are reported.

The first observation of Mo atom production by the collisionless infrared multiphoton dissociation of Mo(CO)₆ with second harmonic radiation (approximately 5 micrometers ) of TEA CO₂ laser is reported. The ground-state Mo (a⁷S₃) atoms have been detected by an UV laser induced fluorescence technique.

We have established that an energy transfer occurs between NO and co-adsorbed CO and N₂ molecules following the photoexcitation of (NO)₂ dimers adsorbed on an MgF₂ substrate. The NO is desorbed in the (v equals 1) states. The photoexcitation of (NO)₂ dimers with mixture of CO or N₂ leads to the desorbtion of NO the co-adsorbed species. Using (2 + 1) REMPI we have found that the CO is desorbed in the (v equals 0) with a rotational temperature of 380 +/- 30 K. The desorbed N₂ and CO have the translational energies lower than of NO.

Laser-induced desorption, dissociation and ionization of dimethylcadmium (DMCd) molecules adsorbed on various substrates have been studied using laser desorption mass spectrometry. These processes are controlled by resonant multiphoton absorption of UV radiation in adsorbate as well as photoelectronic or thermal excitation of substrates. Resonance-enhanced processes in DMCd physisorbed multilayers initiated by KrF laser have been examined. Attempts to realize a purely thermal desorption of this adsorbate due to heating of various substrates by lasers on XeCl, YAG:Nd³⁺, and CO₂ have been undertaken.

Laser driven gas-phase synthesis in a flow reactor was employed for the production of carbon and silicon cluster beams starting from gaseous compounds. It is based on a CO₂-laser-induced decomposition of molecular gases containing carbon and silicon, such as C₂H₂ and SiH4. By introducing a skimmer into the reaction zone, the generated clusters are transferred to the free molecular flow and analyzed with a time-of-flight mass spectrometer. The carbon clusters are characterized by a bimodal distribution. In the region of lower masses C(subscript n clusters were observed up to n equals 19 with the progression n equals 1. In the higher mass fullerenes were observed C₆₀ and C₇₀. Also observed were two types of silicon: clusters with number of atoms up to 12 and also large ones with number of atoms 700 - 1000 which corresponds to nanometer-size. These clusters were deposited on a silicon or sapphire target at room temperature. Micro-Raman spectroscopy techniques were used for characterization of these deposits. In particular for silicon two features in the Raman spectrum were evident: one broad band and a sharp peak which correspondently were attributed to silicon amorphous and crystalline phase and that nanocrystallites deposited on the substrate consist of about 800 atoms (quantum dots with a size of about 3 nm). Thus, the present studies show that the laser-driven nucleation in a flow reactor is a powerful technique to produce fullerenes and silicon quantum dots and other nano- size semiconductors or high-temperature evaporated materials.

Oriented ground state 5²S_1/2 Rb atoms produced in molecular photodissociation had been observed and studied. The cell containing low-pressure RbI vapors was illuminated by pulse circularly polarized laser radiation at 266 nm. Resulting polarized Rb atoms had been detected using transmission monitoring technique in two experimental geometries. Oriented atomic spin precession in an external magnetic field was detected by atomic vapors dichroism.

The vibrational relaxation of CD₃F in solid Xe has been studied at T approximately 160 - 90 K. Measured at near temperatures, gas, liquid and solid phases experimental data are analyzed in a similar way.

The electron-ion pair recombination dynamics in solution of anthracene in methylcyclohexane was investigated by the picosecond photoassisted charge separation technique. The ion pairs was created by the two-photon ionization of anthracene using the 360 and 720 nm laser pulses. The delayed I.R. (1080 nm) pulse excited electrons after the U.V. pulse. The enhancement of photogenerated charge, (Delta) Q, due to additional action of the I.R. laser pulse was measured as a function of the delay time, t_d, between the U.V. and I.R. pulses. Decay kinetics (Delta) Q(t_d) observed was in agreement with the diffusion model of geminate recombination in which the initial spatial distribution of the electron-ion pair has Gaussian form f₀(r) exp(-r²/B²) with B equals 3.5 +/- 0.5 and B equals 5.5 +/- 0.5 nm for the wavelength of U.V. light 360 and 270 nm respectively.

Multiphoton dissociation of dichlorofluoromethane induced by the incoherent superposition of two pulsed infrared laser beams tuned at 927 and 1086 cm^-1 is reported. The experiments were carried out either simultaneously or with a given time delay between both beams in the 1 - 3 J cm^-2 fluence interval, and neat gas pressure in the static cell raging between 0.4 and 2 mbar. Simultaneous and delayed two frequency multiphoton spectra of CF₂Cl₂ are obtained. Some spectroscopic structure in the quasicontinuum is detected and the dependence of the bimodal irradiation dissociation yield on time delay is explained.

A method based on the use of integral transform and orthogonal polynomials is presented to obtain the analytic solutions of the equations for coherent dynamics of multilevel quantum systems as simple molecular models describing molecule-radiation interactions in the high-power laser field and many other processes. As an example the Jacobi polynomials have been used and exact analytic solution has been obtained for dynamics of the family of multilevel Jacobi systems with both equidistant and nonequidistant energy levels, with various dependencies of dipole transition moments on energy, with both resonant and non-resonant laser excitation. Some special cases of the solution for definite systems from the family are given.

The experimental approaches to studying both collision- induced and collision-free vibrational relaxation after excitation of polyatomic triplet molecules by CO₂ laser and by ruby laser pulses are used to discuss the processes of vibrational energy redistribution in quasicontinuum of vibrational states.

Methods are suggested for calculating interatomic potentials of ground and electronically excited states of the diatomic systems. The calculations of potential energy curves of the hydrogen, helium, rare gases and their ions are presented.

The joint influence of electronic excitations and mechanical stresses originated from UV laser action on solids (primarily polymers) decomposition kinetics is discussed.

The effect of permanent hole burning is studied in absorption spectra of quantum sized CdS nanocrystals with the mean diameter of about 30 angstroms and wide size distribution embedded in polymeric film. The selective photoexcitation of appropriate CdS quantum dots followed by their ionization and further irreversible oxidation of CdS phase by holes h⁺ is considered to be responsible for this effect.

The intramolecular energy transfer (IET) in bifluorophoric molecules was researched experimentally and theoretically with the quantum-chemical method. It is shown, that IET realizes through the internal conversion process in bifluorophoric molecules depends on a mutual orientation of a donor and an acceptor and a length of (CH₂)_n- bridge. The coefficient of IET and the lasing efficiency of the bifluorophores were estimated experimentally.

There were received SERS spectra of para- metoxystyrylphtalylium (MSPh) with different roughness of surface of thin silver films (TSF). Spectra were received when applying solutions on the TSF directly and after preliminary acetonitrile treatment. There were discovered considerable differences of SERS spectra of MSPh adsorbed from ethanol solution on annealed and non-annealed TSF (after acetonitrile treatment).

Laser-induced coagulation in biological tissue leads to a significant change of the reduced scattering coefficient (mu) _s. This change can be monitored by phase-demodulation imaging and cw-transillumination techniques in bulk tissue. First results are presented using a 2D optical tomography and a linear scanning system.

Biological responses of cells to visible and near IR (laser) radiation occur due to physical and/or chemical changes in photoacceptor molecules, components of respiratory chains (cyt a/a₃ in mitochondria). As a result of the photoexcitation of electronic states, the following physical and/or chemical changes can occur: alteration of redox properties and acceleration of electron transfer, changes in biochemical activity due to local transient heating of chromophores, one-electron auto-oxidation and O₂^- production, and photodynamic action and ¹O₂ production. Different reaction channels can be activated to achieve the photobiological macroeffect. The primary physical and/or chemical changes induced by light in photoacceptor molecules are followed by a cascade of biochemical reactions in the cell that do not need further light activation and occur in the dark (photosignal transduction and amplification chains). These actions are connected with changes in cellular homeostasis parameters. The crucial step here is thought to be an alteration of the cellular redox state: a shift towards oxidation is associated with stimulation of cellular vitality, and a shift towards reduction is linked to inhibition. Cells with a lower than normal pH, where the redox state is shifted in the reduced direction, are considered to be more sensitive to the stimulative action of light than those with the respective parameters being optimal or near optimal. This circumstance explains the possible variations in observed magnitudes of low-power laser effects. Light action on the redox state of a cell via the respiratory chain also explains the diversity of low-power laser effects. Beside explaining many controversies in the field of low-power laser effects (i.e., the diversity of effects, the variable magnitude or absence of effects in certain studies), the proposed redox-regulation mechanism may be a fundamental explanation for some clinical effects of irradiation, for example the positive results achieved in treating wounds, chronic inflammation, and ischemia, all characterized by acidosis and hypoxia.

The basic principles of coherence-domain optical methods accounting their application to cell structures and biotissue function monitoring are considered. Using designed 2D-scanning speckle microscope human skin epidermis and human sclera structures were investigated. Frequency-domain technology was used for in vivo and in vitro analysis of human skin and sclera optical characteristics.

Laser backscattering nephelometry is used to retrieve information on the kinetics of structural changes of erythrocytes in whole blood due to aggregation and deformation in shear flow in vitro. Laser Doppler microscopy is used to monitor nonstationary blood flows in single vessels in vivo. Monte-Carlo numerical analysis of Doppler signal is given for the case of highly scattering tissue surrounding of low. This case is related to in vivo blood perfusion measurements.

Method of measurement of basic parameters for intramolecular transitions in organic compounds solutions is discussed. The values of triplet quantum yield and lifetimes for a number of solitons of the phthalocyanine derivatives and related compounds have been measured. The possibility of measurement of intramolecular parameters and dissolved oxygen concentration was shown on an example of aqueous solutions used in clinic for diagnostics and photodynamics therapy of cancer.

The liquid crystalline medium `lipid-water' is considered as the plane fractal object with fractal dimension Di equals 3. Controlling of hydrate complex (`lipid-water') molecules packing and conformation is carrying out by the IR-induced excitation of intramolecular vibrations of the lipid functional groups (P-O-C, C equals O, P equals O, C-O-C) and the water one (OH).

Problems of studying low-intensity laser radiation effects on lyotropic medium are associated with a search for physical mechanisms of therapeutic biostimulating action of the radiation type under consideration' . Since such an effect is detected in a large frequency an2 ,lyotropicmedia without photoacceptors which could absorb laser radiation selectively are of special interest. Optical properties of sonated systems analogous to water-lecithin mixtures are determined by a type of interaction of mesogene molecules with water. The hydration and dehydration processes taking place in such systems under external force influence change their sonification properties and their investigation can yield an important information about the type of alterations occurred.

The UV fluorescence spectra of aromatic amino-acids and some proteins at two photon excitation by second harmonic of Nd:YAG laser are received. Two-photon absorption cross sections of tryptophan, tyrosine, phenylalanine and proteins: bovine serum albumin, lysozyme, trypsin, (alpha) - chymotrypsinogen and pepsin at wavelength 532 nm were measured by means of the two-quantum standard method.

The effect of protein and matrix modifications on the photoanisotropic properties is studied for developing the concept of impact upon the main optical properties of the dynamic optical material based on bacteriorhodopsin (BR) both interaction of transmembrane protein--chromophore complex BR with matrix and interaction of protein opsin with chromophore retinal. Also possibility of the application of BR-films for the light polarization modulator is proposed.

The results are presented of the study of intracellular localization of Co-phthalocyanines. The methods were used of Raman and fluorescence microspectroscopy.

A new measuring technique of statistical parameters of transparent or reflecting random phase objects is discussed. The technique is based on the usage of the probing spatially-modulated laser beam (beam with regular interference pattern), focused on a moving object, and on measurement of contrast of average intensity fringes, formed in scattered dynamic speckle-modulated field. The behavior of the speckle field interference induced by the focused spatially-modulated laser beam diffraction on the random phase objects has been studied. The dependence of dynamic field average intensity fringes contrast on the object parameters has been established. The divergencies of the illuminating beam and the scattered light were taken into account.