A non-destructive Raman spectroscopy has been widely used as a complimentary method to X-ray diffraction characterization of Cu2ZnSnS4 (CZTS) thin films, yet our knowledge of the Raman active fundamental modes in this material is far from complete. Focusing on polarized Raman spectroscopy provides important information about the relationship between Raman modes and CZTS crystal structure. In this framework the zone–center optical phonons of CZTS, which is most usually examined in active layers of the CZTS based solar cells, are studied by polarized resonant and non-resonant Raman spectroscopy in the range from 60 to 500 cm−1 on an oriented single crystal. The phonon mode symmetry of 20 modes from the 27 possible vibrational modes of the kesterite structure is experimentally determined. From in-plane angular dependences of the phonon modes intensities Raman tensor elements are also derived. Whereas a strong intensity enhancement of the polar E and B symmetry modes is induced under resonance conditions, no mode intensity dependence on the incident and scattered light polarization configurations was found in these conditions. Finally, Lyddane-Sachs-Teller relations are applied to estimate the ratios of the static to high-frequency optic dielectric constants parallel and perpendicular to c-optical axis.

We show that when polystyrene is exposed (for 15-60 sec) to a UV laser light beam (λ = 248 nm), its absorption and luminescent properties change significantly. In the irradiated polymer, optical centers are formed with absorption bands in the 280-460 nm region and fluorescence bands in the 330-520 nm region. We have established the chemical structure of the optical centers for fluorescence of polystyrene.

Polymer films with small Ag-clusters and Ag-nanocrystals were obtained by the cocondensation of Ag and chloro-p-xylylene from the gaseous phase followed by low-temperature solid-state polymerization. UV-Vis spectroscopic data show that the annealing of films at ambient temperature and thereafter at 373 K leads to a sharp rise of the amount of Agnanocrystals by aggregation of small clusters, but the mean size iof the nanocrystals remains practically constant. According to X-ray data, the lattice of Ag-nanocrystals is close to that of metallic Ag and i i s equal to approximately 50 A.

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We have established that exposure of polystyrene-based scintillator samples to UV laser radiation (248 nm) leads to a significant decrease in the fluorescence intensity. We have carried out a spectral analysis of the luminescent and absorption properties of the scintillator, which allowed us to determine the major factor in the decrease in luminescence intensity of the samples exposed to UV radiation. We propose a new hypothesis for the mechanism of the processes leading to the decrease in light output of the scintillator during operation. Introduction.A plastic scintillator is a composite consisting of an optically transparent plastic and added luminophores. A plastic scintillator displays bright luminescence when exposed to ionizing radiation and is rather stable relative to such exposure. Scintillators are made from such composites in the form of optical fibers, films, and plates with large surface area, and also bulk blocks of any size or shape, which significantly expands the possibilities for their application. The advantage of plastic scintillators is their fast response (the radioluminescence lifetime ranges from fractions of a nanosecond to several nanoseconds). They are used for radiation detection and dosimetry.The most widely used plastic scintillators are based on polystyrene with added luminophores: p-terphenyl (p-TP) and 1,4-bis(2-(5-phenyloxazolyl))benzene (POPOP). Polystyrene plastic is the most radiation resistant among the known synthetic polymers [1]; it has high transparency over a broad spectral range (λ > 290 nm). However, we should point out that the indicated characteristic is seen only in the very pure polymer. Commercial polystyrene contains impurities and structural defects absorbing in the 290-400 nm region [2][3][4].A general disadvantage of plastic scintillators is gradual loss of scintillation efficiency during operation. As the absorbed dose of ionizing radiation increases, the light output of the scintillator decreases. As the characteristic for radiation resistance, we take the value of the absorbed dose D 1/2 at which the light output is half of the initial value. For polystyrene scintillators, D 1/2 ≈ 600 kGy [3].The radiation-induced physicochemical changes leading to a decrease in the light output of a plastic scintillator have been the subject of many studies [3,[5][6][7][8][9][10]. Special attention has been focused on the loss of transparency in the plastic. It has been established that this is due to the appearance of "induced" absorption bands that are relatively intense in the 300-400 nm region and low-intensity in the visible region. The bands that appeared were assigned to macroradicals formed on exposure to radiation, some of which proved to be short-lived while others were rather stable. These data provided the basis for established ideas about the reasons for radiation-induced wear in plastic scintillators. We should point out that in some papers (see, for example, [9]), bands were seen which could not be attributed to radicals, and they were assigned to unident...

The effect of constant magnetic fields on dislocation anharmonicity of p type silicon single crys tals with a conductivity of 6 Ω cm has been studied. It has been found that preliminary exposure of dislocation silicon (with a dislocation density of 10 4 -10 6 cm -2 ) to a constant magnetic field (B = 0.7 T, t = 30 min) at room temperature causes a change in the nonlinear fourth order elastic modulus β d . The observed changes are associated with the dynamics of magnetosensitive complexes of structural defects and, hence, with the changes in the length of the vibrating dislocation segment. Based on the dynamics of β d (t) after sample expo sure to a magnetic field, the conclusion is made about an increase in the vibrating dislocation segment length L d by 30%, and the characteristic relaxation times of observed effects are estimated.