Rumyantsev V. Interaction of the electromagnetic radiation and light particles with imperfect crystalline media

In the thesis the results of systematic studies of the interaction of electromagnetic radiation and light charged particles (beta-particles) with imperfect crystalline media are presented. Dispersion of polaritons in bulk cryocrystals and diamond-like structures is investigated. Dispersion laws for balk light?excitons in semi-infinite atomic cryocrystals are studied in framework of the local field method with account of crystal surface structure. Effect associated with response of a quasi-two-dimensional diamond-like layer to the moving electron field is considered too. Beta-particle field induces exciton modes to arise in the layer. Coupled with the beta-particle electromagnetic modes they generate polaritons. Spectral density of the radiation intensity of the flashed polaritons has been estimated as a function of the layer thickness as well as of the scattering angle and the beta-particle velocity. Excitonic spectra of molecular crystals with defects such as two-sub-lattice orientationally disorderedcrystals obtained by the way of the numerical calculation. In the thesis a photonic crystalline superlattice is modeled as a set of macroscopically homogeneous layers with randomly included extrinsic (with respect to the ideal superlattice) layers of a variable thickness and composition. The polariton spectrum of a non-ideal superlattice with an arbitrary number of layers per elementary cell and dependence of the band gap width upon concentration of admixture layers and refractive index peculiarities is analyzed. We have investigated light scattering by c-oscillations of the apical oxygen O(4) ion, which has a specific role since the superconductive pairing mechanism is due to the fluctuation of O(4) positions in YBa2Cu3O7-x-type crystals. When oxygen vacancies are in the O(4)-Cu(1)-O(4) bridges (or another distortions of lattice symmetry) the c-vibrations of O(4) result in initiation of a dipole moment and at the same time they are associated with the Cu(1)-O(4) bond deformation. Thus Raman scattering by dipole-active O(4)-oscillations is caused. Calculations of intensities of both Raman light scattering (spontaneous and stimulated) and second optical harmonic generated by the surface layers of a YBa2Cu3O7-x single crystal are presented. Features of characteristics of normal electromagnetic waves in a molecular crystal, caused by an external mechanical pressure are investigated. In framework of an exciton model microscopic expression for dielectric permeability tensor of the homogeneously deformed crystals and rotational ability of the crystals (having C3v , C4v , C6v C3h , D3h , Td symmetries) is received.