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The deviation angles of the O-H bond for water molecules in the gaseous state are calculated ab initio. The Hartree-Fock method with various basis sets of the Gaussian 09 package is used. The calculation results correlate with previous estimates based on experimental data.

The force matrix of the SO2 molecule is calculated without using a priori assumptions on the nature of the force field. The calculations are performed using a comparatively new 3N-matrix method based on the experimental frequencies of characteristic normal vibrations of 32S16O2, 32S18O2, and 34S16O2 molecules. It is shown that the direction of the chemical bond between chemically bound S and O atoms does not coincide with the direction of the straight line that connects the nuclei of these atoms. The angle between these directions (deviation angle) is determined. In the approximation of harmonic vibrations, the deviation angle is Δ = 1.092°. The effect of the anharmonicity of vibrations on the deviation angle is evaluated.

Hydrogen bonds and their fluctuations are one of the factors that determine the unique properties of water [1]. Building models of formation and rupture of hydrogen bonds due to non-eigen vibrations of a molecule of water is to a large extent determined by the availability of accurate information on the geometric structure of the water molecule. Geometric parameters of the water molecule have been well studied for the gaseous state. This was aided by the possibility of an experimental study of the regularities in the rotational spectra of molecules. However, some questions about the geometry of the water molecule in the liquid state remain unanswered. For example, many sources state that the valence angle of the water molecule decreases during the transition into the liquid state [2]. Based on the experimental data of molecular vibration spectra in D 2 O and H 2 O molecules [3], the authors have estimated valence angle of water in the liquid state. Consequently, the value of the valence angle of water in liquid state was determined to be (89 ±2)°. A question of determination of libration vibrations of water molecule, as well as the analysis of its consequent inversion doubling, based on the new information on the equilibrium angle of the water molecules in the liquid state, constitutes an interest and is discussed in the present paper.

The optical absorption and luminescence properties of indium-doped sodium borate glass irradiated by γ-rays and by powerful UV lasers within the impurity-related absorption band are investigated experimentally. It is demonstrated that both the laser- and γ-irradiation cause similar transformations of optical spectra in the UV and visible regions. The changes of the spectra observed are described with the use of a model which includes three types of impurity centres formed by differently charged indium ions.

This research is devoted to the vibrational spectroscopy inverse problem solution that gives a possibility to design a molecule and make conclusions about its geometry. The valence angle finding based on the usage of inverse spectral vibrational spectroscopy problem is a well-known task. 3N-matrix method was chosen to solve the proposed task. The usage of this method permits to make no assumptions about the molecule force field, besides it can be applied to molecules of matter in liquid state. Anharmonicity constants assessment is an important part of the valence angle finding. The reduction to zero vibrations is necessary because used matrix analytical expression were found in the harmonic approach. In order to find the single-valued inverse spectral problem of vibrational spectroscopy solution a shape parameter characterizing “mixing” of ω 1 and ω 2 vibrations forms must be found. The minimum of such a function Υ called a divergence parameter was found. This function characterizes method’s accuracy. The valence angle assessment was reduced to the divergence parameter minimization. The β value concerning divergence parameter minimum was interpreted as the desired valence angle. The proposed method was applied for water molecule in liquid state: β = (88,8 ±1,7)° . The found angle fits the water molecule nearest surrounding tetrahedral model including hydrogen bond curvature in the first approximation.

Comprehensive investigations of luminescence, excitation, and absorption spectra as well as of the luminescence kinetics of a frozen LiCl-Tl+ solution are carried out. It is established that the luminescence spectrum consists of four components. One component is caused by luminescence of the matrix and the remainder by luminescence of one luminescence center, namely, by the saturated complex of thallium TlCl2(H2O)Cl4. The absorption spectrum consists of three components. Their parameters have been evaluated. Each component of the luminescence spectrum is excited in several components of the absorption spectrum. It is found that the luminescence spectrum components and their intrinsic absorption bands are located differently on the frequency axis. These data are similar to those obtained for other activated solutions of electrolytes.

The authors` studies have shown that three types of Tl{sup +} luminescence centers are formed in Tl{sup +}-activated chlorine-containing sodium-borate glass. These centers differ from one another in the number of Cl{sup -} ions contained in the first coordination sphere of Tl{sup +}. They were identified accordingly as 0-, 1-, and 2-centers of Tl{sup +}. The excitation (ES) and luminescence (LS) spectra of the 1- and 2-centers of Tl{sup +} are shifted into the region with lower energies in comparison with the spectra of 0-centers of Tl{sup +}, the LS of the 0-centers of Tl{sup +} are overlapped by the absorption spectrum (AS) of Gd{sup 3+} ions, and the LS of the 1- and 2-centers of Tl{sup +} overlaps the spectral range containing Tb{sup 3+} absorption lines. In view of the data on the overlapping of LS of Tl{sup +} ions in sodium-borate glasses by AS of REI (Gd{sup 3} and Tb{sup 3+}), one can expect effective radiationless energy transfer (RLET) Tl{sup +} {yields} Gd{sup 3+} and Tl{sup +} {yields} Tb{sup 3+}, which is an object of study in the present work.

Radial d and s electron wave functions have been calculated for Tl+ in the 5d106s2 configuration in a crystalline field. One corrects for the effects of the nonpoint lattice ions on the wave functions by means of an approximation in which the lattice is considered as a set of charged spheres. The calculations are performed in the central-field approximation by the Hartree-Torrance method without allowance for the exchange interaction. The nonpoint correction leads to some consolidation of the wave functions by comparison with the point-ion approximation. The energy eigenvalues for the d and s electrons are altered. The calculations agree with increase in the binding energy between the central ion and the ligands in thallium halide complexes in the series Cl−→Br−→I−.

We describe a method of solving the inverse spectral problem which is applicable to free molecules as well as to molecules in a medium. We give a criterion for the uniqueness of the definition of the force matrix. This criterion links the necessary number of normal proper vibrations of a molecule with a number of necessary form parameters. We calculate the force matrix of tetrahedral molecules CH4, CD4, and CT4. When we use zero-point values for frequencies of normal vibrations the relative discrepancy in the corresponding force-matrix elements does not exceed 0.3%.