Variable-temperature Raman studies were carried out for some representatives of a novel class of industrially promising (sigma) -conjugated polymers-polymetallanes of the type (R₂M)_n, M equals Si, Ge, Sn. Electronic-conformational nature of the thermochromic phase transitions of order- disorder type exhibited by some of these polymers was investigated. The applicability of Shorygin's semi-classical approach to the pre-resonant Raman intensity enhancement was confirmed experimentally by the example of polysilanes.

Raman spectra (RS) of (100) GaAs implanted with 140 keV Si⁺ ions, both before and after annealing, were obtained at room temperature, in x(yz)x backscattering geometry, using the 514.5 nm line of Ar laser. The implantation-induced amorphous bands and LO-line shape changes were observed with increasing fluences from 10¹³ to 5 X 10¹⁴ cm^-2. We explained the modifications of the spectra via disorder-induced selection rule breakdown and estimated nanocrystallite size for different fluences according to the model of reduction of the spatial correlation length. For annealing studies implanted samples were capped with Si₃N₄ layer and annealed at 900 C for 20 min in hydrogen. After annealing, the amorphous bands have disappeared, and the new spectral features were observed. We examples the evolution of the spectra by the dopant activation, resulting in RS by phonon- plasmon coupled modes and RS by LO phonon, originating from the surface-depletion layer. We interpreted shifts of the coupled modes and LO intensity change as evidence of the carrier concentration variation with fluences. Experimental result were described by the Lindhard-Mermin dielectric function including the non-parabolicity of the conduction band, evaluated for the case, when Drude approximation is not available. From Raman line-shape analysis we have obtained that the value of carrier concentration were 10¹⁸ cm^-3 for ion fluences 10¹³-5 X 10¹⁴ cm^-2.

Raman scattering (RS) spectra of the crystalline (alpha) - sulphur are investigated at room and liquid helium temperatures. The doublets and quartets are found in the RS- spectrum at helium temperature in a frequency range, corresponding to the intramolecular vibrations. An explanation of the observed splitting is given with a help of the group theory analysis of intramolecular vibrations, affected by the crystalline field. The shifts of the spectral position of characteristic peaks in the RS-spectrum of the (alpha) -sulphur are measured with the temperature variation.

In this article we consider features of intensity distribution of the Raman scattering by non-ordinary polaritons in the frequency - wavevector coordinates. The most simple instances of scattering in the crystallographic symmetry plane of an orthorhomibic crystal are described to illustrate the main different between nonordinary polaritons spectra and ordinary ones. It is supposed that a polariton wavevector orientation is constant for each spectrum. We discuss also the actual experimental situation with scattering by polaritons in (alpha) -iodic acid crystal near the frequency of the valency OH-bond taken as an example.

Raman spectra of LiB₃O₅ and Li₂B₄O₇ crystals have been studied. Raman scattering efficiency and oscillator strengths of some polar vibrations were estimated. Contribution of various vibrations to nonlinear optical coefficients according their assignment has been discussed. Influence of K⁺ and Ag⁺ impurity ion on Raman spectra of Li₂B₄O₇ have been studied. Anomalies of the isofrequency temperature dependencies of Raman spectral intensity observed at T equals 235 K are interpreted in terms of the translation structural phase transitions.

The Raman and IR spectroscopic investigations are presented of the thiocyanates: LiSCN, NaSCN, KSCN, RbSCN, CsSCN; nitrates: Ca(NO₃)₂, Sr(NO₃)₂, Ba(NO₃)₂, Pb(NO₃)₂; and perrhenates: LiReO₄ NaReO₄ KReO₄ in the region of a solid-liquid phase transition. The differences in a pre-melting behavior of these salts were found which can be attributed to a different geometry of the SCN^-, NO₃^- and ReO₄^- anions.

Raman scattering spectra of CsScF₄ crystal has been studied under high temperature and pressure. Soft mode condensation was observed below tetragonal-tetragonal phase transition under heating, and lattice dynamics simulation of the upper phase has been performed to clarify the form of the unstable mode. New first order phase transition has ben found under high pressure, new high pressure phase is supposed to be of low, C_2h², Z equals 4 symmetry, the same as in KAlF₄ crystal.

Spectra of the Raman scattering (RS) by transverse and longitudinal A₁-vibrations in crystals of the lithium niobate and lithium tantalate are investigated at room and liquid helium temperatures. An essential decrease of the RS- linewidths for scattering by A₁T-phonons is found in the course of deceasing from room to liquid helium temperature. The obtained results show that coherent excitation of polariton modes in ferroelectrics is a promising method for generating the frequency-tunable submillimeter-band radiation.

A new experimental method for the investigation of structure of oriented polyethylene (PE) by Raman spectroscopy is proposed. The method is based on decomposition into two separate lines the Raman line around 1300 cm^-1 assigned to CH₂-twisting vibrations. The decomposed lines are associated with polymer chains of crystalline and amorphous regions in structure of PE. It is assumed that the analytical relationships between the second and forth coefficients in the expansion of the orientation distribution function in a series of Legendre polynomials and the depolarization ratios previously obtained for the vibrations with B_2g + B_3g symmetry are valid for each line. It implies that the orientation parameters can be calculated separately for both crystalline and amorphous regions. The integral intensities of the decomposed liens have been used to estimate crystallinity. To eliminate the effects of orientation and high numerical aperture objective correction procedures were introduced. The structure changes in ultra high molecular weight PE upon draw ratio have been studied by this method. It was shown that valuable information could be obtained concerning the efficiency of fibrillar structure formation.

Brief overview of peculiarities of Raman scattering in gyrotropic crystals treated as effects of spatial dispersion is presented. Raman experiment in gyrotropic crystals, elimination of artifacts, spectroscopic manifestation of gyrotropy in phonon Raman spectra, exchange with angular momentum between light and crystal lattice excitation and corresponding selection rules are discussed.

Raman scattering and anti-Stokes photoluminescence spectra of the crystalline GaP, ZnSe and ZnTe are investigated at room and liquid helium temperatures. The increase of quality-factor of vibrational modes and sharpening of polariton band are found in the Raman spectrum at liquid- helium temperature in a frequency range, corresponding to the TO and LO vibrations. A tentative explanation of the observed anti-Stokes photoluminescence is given with a help of the deep-level state analysis of these materials. The low-temperature anti-Stokes photoluminescence is found to be a common property of the wide gap semiconductors and can probe the spatial distribution profiles of impurities in these crystals.

The results of spectral investigation of two liquid crystalline isomers at different temperature pre-history are reported. The temperature depended transformations of vibrational Raman spectra and their connections with the change of structure of these substances were investigated. Spectral region was 1100-1760 cm^-1, temperature interval was from 203 K to 398 K. Both general and special regularities under thermo-structural transformations were noted.

For the first time the Raman spectrometric study for determination Gibbs free energy of the formation (Delta) G_f and Henry's constant in high-temperature water solution was used. We studied the system S_1q-H₂O at 200-360 degrees C and the pressure of the saturated water vapor. The values (Delta) G_f as a function of temperature for the aqueous species H₂S_(aq), SO_2(aq) and S_8(aq) were calculated after determination of the equilibria constant between species of the system. We determined 8-term ring molecules S_8(aq) as the predominant species of the elementary sulfur in a water solution. The quantitative data were obtained using the Raman intensity of the strength vibration of water as the internal standard. The design of the autoclave provided the possibility of measuring the distribution of components between liquid and gas for Henry's constant determination.

The IR and Raman spectral-structural-phase correlations in a series of the 4-cyano-4'-n-alkoxybiphenyles are studied. The analysis of Q(C equalsV N) band behavior in the solid crystal (SC), liquid crystal (LC), isotropic liquid (IL) and hexane solution is carried out. The changes of the spectral parameters of several vibrational bands at phase transitions were interpreted as being caused by conformational changes of the nOCB molecules. The mechanism of intradimer energy transfer explaining the Q(C equalsV N) band breadth in the LC and IL phases is investigated in detail.

It is shown that the Fermi-splitting of v₃ and 2v₂ vibrations of NCO^- anion in aqueous solutions of potassium cyanate linearly increases with the concentration of NCO^-. This concentration dependence is due to the existence of coherent excitation transfer between molecular anions in aqueous solutions. The experimental data are compared with the theoretical calculation results. Our estimates show that the time of the v₃ excitation transfer between molecular anions NCO^- is shorter than the characteristic diffusion time in the investigated solutions.

The beam profile of stimulated Raman scattering (SRS) in a Kerr medium pumped by multimode radiation with regular structure having nearly four-fold azimuthal symmetry was studied. The SRS was excited near the threshold of generation by nanosecond pulses of laser radiation at wavelength 530 nm. The profile of output pump beam had a uniform intensity distribution, whereas the SRS beam profile showed kaleidoscopic change from shot to shot, while the energies of input pulses were kept stable. The circularly distributed speckle pattern, as well as interference fringe structure in the profile of the beam of SRS I Stokes components was observed. The interference fringes showed the number of points with origination and vanishing of fringes. Such behavior, which is the vortex signature, allows to suppose that SRS waves, generated from quantum noise, carry the screw dislocations. The origin of dislocations is analogous to one described for a speckle field and discussed for SRS.

Propagation of the wave of Stimulated Raman Scattering (SRS) in waveguide is studied, on conditions that it is filled with some Raman-active material and that a pump wave is present inside. The features of the SRS-wave are analyzed, assuming the wave frequency to be close to the critical value.

Experimental investigations of the energetical, spatial and statistical properties of stimulated Raman scattering (SRS) pulses, excited in acetone by picosecond laser pulses, are presented. The properties of the SRS pulses propagating in the forward direction and propagating in the backward direction are compared. Changing the geometrical and energetical conditions of excitation one can change the properties of SRS pulses in proper way.

The process of stimulated Raman scattering is described by the model of 2D oscillator. The photons of Stokes mode are described by one mode of the oscillator and phonons of the medium are described by the other mode of oscillator. The interaction of photons and phonons is taken to be quadratic in the creation and annihilation operators of the photons and phonons. New time-dependent integrals of motion are found for stimulated Raman scattering within the framework of this model. The photon-phonon probability-distribution function is found in terms of Hermite polynomials of four variables. It is shown that the squeezing phenomenon can be transferred from one mode to the other due to interaction. The statistical dependence appears due to interaction as well. An explicit formula of the photon-number probability distribution as a function of the laser-field intensity and the medium parameters is obtained both in terms of Hermite polynomials of two variables and in terms of Legendre polynomials after the averaging of the photon-phonon probability-distribution function over the phonon mode. The mean photon number and its dispersion in the Stokes mode are expressed as functions of the medium parameters and a parameter of the interaction. It is shown that if the medium is initially prepared, then after the interaction with laser field the photons are created in squeezed state. The classical propagator for stimulated Raman scattering is found within the framework of the symplectic tomography scheme.

We present the review of femtosecond SRS generation and amplification in compressed gases. the aim of our work is to study SRS spectral and temporal structures in compressed gases with femtosecond light pulses and to optimize conditions of excitation in order to obtain pulses with the desired spectral, temporal, and energy properties. In what follows, we present the result of our studies of SRS amplification in compressed hydrogen pumped by femtosecond pluses of the second harmonic of radiation of a titanium- doped sapphire laser. Our aim was to estimate the feasibility of increasing efficiency of SRS conversion and the potentialities of using transient SRS for spectral-time selection and amplification of weak signals.

The conditions when faster-than-light Raman pluses can appear are discussed. The formula connecting the shape of a pulse with its velocity is found.

Brief description of NSOM technique applicable for biology and medicine has been introduced. The advantages of combining NSOM technique and TCSPC technique are being demonstrated for obtaining the highest possible spatial resolution.

This paper presents a review of the studies on using laser autofluorescent and Raman spectroscopies in tumor diagnostics. Peculiarities of spectroscopy by different wavelength lasers and different organs is described. Prospects of the diagnostics method is discussed.

Spectra of photoluminescence of bacterial suspension of different concentrations and DNA suspension are represented in given paper. The photoluminescence was excited by laser UV radiation. The investigated microorganisms were in a spore condition. The luminescent spectra, excited by the radiation of different intensities were recorded. Evolution of photoluminescent spectra in dependence on changing of bacterial suspension's concentration and delay time of a strobe-pulse of registration system was defined. We have also established that the photoluminescent spectra of investigated samples were situated in a near-UV-blue spectral region. Difference of photoluminescent spectra of bacterial samples that were preliminarily irradiated by tough UV light and so absorbed different doses of UV energy from spectra of non-irradiated bacterial samples was notices. Kinetics of luminescent level during the irradiation by laser UV light was investigated.

Theory of the resonant hyper-Raman scattering of light by the longitudinal optical phonons in semiconductors which include excitonic effects has been developed. The theory can be applied at double frequency of incident radiation below and above the band gap. The matrix elements corresponding to the transition between different exciton states are calculated analytically. The contributions of the discrete and continuous states to the hyper-Raman intensity are compared.

Hyper Raman Scattering (HRS) is considered as a convenient tool of studying the interface region of the metal- semiconductor contact. The effect of the band bending near the interface results sometimes in an accumulation of free carriers near the interface. The strong inhomogeneity is shown to induce local changes of the sign of the dielectric permittivity and in the consequent strong enhancement of the HRS intensity. The application of a bias potential is shown to govern the enhancement process.

The investigation of Hyper Rayleigh and Hyper Raman Scattering of light in ferroelectrics Pb₅Ge₃O₁₁ and LiNbO₃ executed. Excitation of hyperscattering spectra was realized by means of picosecond laser emission with peak power density at the sample approximately equals 30 GW/cm². The correlation between registered hyperscattering and spontaneous Raman spectra was established.

The spectra of Raman scattering and photoluminescence of porous Si, Ge, GaP and carbon nanocrystals are investigated at room temperature. The deduction that porous structures consist of isotropic nanoparticles, which have a crystalline kern is made. Using GaP as an example, it can be shown, that nanocrystals, obtained by an electrochemical etching have more perfect crystalline structure than the initial monocrystal. The interaction of phonon modes for nanocrystals create by an electrochemical etching of Si/Ge_xSi_1-x superlattices was observed. The intensive photoluminescence of graphite particles was observed.

Polarized room-temperature Raman spectra of 1D spin-Peierls single crystal (alpha) '-NaV₂O₅ are obtained in backscattering geometries which enabled one to observe all types of the Raman active modes. The Raman spectra of this crystal with various degrees of the deficiency of the Na atoms are also represented. The Raman data are consistent with the recent x-ray measurements and confirm the centrosymmetrical structure of this crystals at room temperature.

First in the world literature comprehensive digital complementary vibrational spectra collection of polymer materials and search system was developed. Non-destructive combined analysis using complementary FT-Raman and FTIR spectra followed by cross-parallel searching on digital spectral libraries, was applied in different fields of forensic sciences. Some unique possibilities of Raman spectroscopy has been shown in the fields of examination of questioned documents, paper, paints, polymer materials, gemstones and other physical evidences.

Some modification of the YBaCuO phase analysis method using the Raman spectra is proposed. It is based not only on the analysis of the corresponding Raman band maxim positions, as usually, but on the analysis of the integral contours of these bands as well. The 400-500 cm^-1 region of Raman spectra of the YBaCuO single crystals was studied for this purpose. The proposed method was realized in original PC-program, which allows fulfilling an express, non- destructive and local phase control for HT SC samples.

Wideband frequency transformation of copper vapor laser radiation has been achieved by stimulated Raman scattering and four-wave mixing processes in lowmode quartz fibers. A study has been made of the spectral distribution of fiber output as a function the fiber length, peak, input power and the angle of the fundamental beam incidence into the fiber. Changing length and the diameter of a fiber give possibility to generate various components as SRS, and component of the four-photon scattering in a spectral range up to 9000 cm(superscript -1).