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We studied the incorporation of Mg-related impurity centers in GaN crystals depending on the direction of the crystallization front. Two series of GaN crystals – (i) undoped and (ii) Mg-doped – were grown by High Nitrogen Pressure Solution (HNPS) method under otherwise identical conditions. Each series contained four samples with ( 10 1 ¯ 0 ) , ( 11 2 ¯ 0 ) , ( 20 2 ¯ 1 ¯ ) and ( 20 2 ¯ 1 ) orientations. The low-temperature photoluminescence (PL) spectroscopy was used for characterization of the obtained crystals. The observed differences in the PL spectra of GaN:Mg crystals suggested that Mg incorporation in GaN grown by HNPS method depends considerably on the orientation of crystallization front. The concentration of Mg impurity incorporated into the GaN crystals subsequently increases for the following sequence of planes: ( 10 1 ¯ 0 ) , ( 11 2 ¯ 0 ) , ( 20 2 ¯ 1 ¯ ) and ( 20 2 ¯ 1 ) . For ( 10 1 ¯ 0 ) , ( 11 2 ¯ 0 ) and ( 20 2 ¯ 1 ¯ ) planes the blue band is related only to ON – MgGa donor-acceptor pair (DAP) transitions, while for ( 20 2 ¯ 1 ) plane the incorporation of Mg-H complexes occurs additionally to the formation ON – MgGa DAP.

Caesium iodide is one of the most extensively studied scintillators. Here, we present X-ray luminescence spectra, scintillation light output and decay curves as a function of temperature, from room temperature down to below 10 K. Features of the observed intrinsic luminescence are explained in terms of radiative recombination of on- and off-center STE. A model permitting interpretation of the dynamics of luminescence changes in CsI with temperature is suggested. This model includes adiabatic potential energy surfaces (APES) associated with singlet and triplet states of self-trapped excitons (STE) and explains the variation of the luminescence spectra with temperature as a result of re-distribution in the population between on- and off-center STE. The temperature dependence of the scintillation light yield is discussed in the framework of the Onsager mechanism.

Results are presented on our latest research, aimed at the development and study of oxide scintillation crystals (ZnWO4, ZnMoO4, PbWO4, PbMoO4, and MgWO4) with high scintillation yield and low intrinsic radioactivity. We report on the improvement of these properties for conventional scintillators, as well as on new promising crystals based on metal tungstates and molybdates. The results are discussed in view of applying these materials in cryogenic experiments searching for dark matter and/or neutrinoless double beta decay. © 2006 IEEE.

Single crystals of Mg-doped GaN grown by high nitrogen pressure solution method in different crystallographic directions ([0001], [101̅1], and [101̅1̅]) were investigated in order to determine thermal stability of their electrical and optical properties. Obtained dependences of resistivity, the Hall coefficient and energy shift of Mg-related photoluminescence peak on annealing temperature allow to suggest that incorporation of Mg in GaN is significantly influenced by the direction of the crystallization front.

The technique, which allows to consider the effect of the geological structure on the seismic wave field was developed. It was tested at Subbotina field within the Kerch shelf of the Black Sea. Computation methodic of common shot point synthetic seismograms in sequential complicated model of the geological media was used. The results of synthetic modeling showed high convergence with real data.

The variation of luminescence and excitation spectra of titanium doped Al2O3 for the concentration of Ti ranging from 10 to 1000 ppm was investigated using synchrotron radiation. In the lightly doped Al 2O3-Ti (

Results are presented of our latest research, aimed at the development and study of oxide scintillation crystals with high scintillation yield and low intrinsic radioactivity. We report on the improvement of these properties for conventional scintillators, as well as on new promising crystals based on metal tungstates and molybdates. The results are discussed in view of applying these materials in cryogenic experiments searching for dark matter or neutrinoless double beta decay. ©2008 IEEE.

The importance of luminescent tungstates and molybdates in several technological applications motivated the study of the structural, luminescence and scintillation properties of the MgWO4-MgMoO4 system. X-ray diffraction studies allowed the identification of three main types of structures in the pseudo-binary MgWO4-MgMoO4 system (sanmartinite β-MgMoO4, cuprosheelite α-MgMoO4, and wolframite MgWO4) and the refinement of the parameters of the crystal lattice. It is found that the single-phase solid solution MgMo 1-xWxO4 with a β-MgMoO4 structure is created only at x