A comprehensive study of the electronic structure of trinuclear molybdenum complexes (NH4)2[Mo3S13] and [Mo3S7(dtc)3]Br with cluster core {Mo3S7} and [Mo3S4(tu)8H2O]Cl4 complexes with cluster core {Mo3S4} is conducted by X-ray emission spectroscopy (XES), X-ray photoelectron spectroscopy (XPS), X-ray absorption near edge structure (XANES) spectroscopy, and quantum chemistry methods. Data were obtained on the partial atomic composition of the highest occupied molecular orbitals and unoccupied molecular orbitals and the nature of atomic interactions within cluster cores.

The results are considered of calibration of semiconductor detectors of the VUSS-E spectro- photometer intended for monitoring the solar ultraviolet radiation flux in the Lyman-alpha line (L, 121.6 nm) on Roshydromet geostationary satellites. The calibration was carried out at the Kosmos metrological station at the Siberian International Center for Synchrotron Radiation in the channel of the VEPP-4 relativistic electron storage ring. The contribution P to the VUSS-E signal from the L line and from the spectral region above ~122 nm is calculated using the model ultraviolet radiation spectra. It is shown that the value of P can vary greatly for different sensors and different levels of solar activity: P ~ 30-60% at a low level and P ~ 50-70% at a high level of solar activity. This result indicates a need to calibrate all channels of each flight instrument and to take into account the dependence of the contribution P to the VUSS-E signal from the L line on the level of solar activity when monitoring space weather.

Методами рентгеновской эмиссионной спектроскопии (РЭС), рентгеновской фотоэлектронной спектроскопии (РФЭС), рентгеновской спектроскопии поглощения (XANES) и квантовой химии проведено детальное исследование особенностей электронной структуры трехъядерных комплексов молибдена (NH4)2[Mo3S13] и [Mo3S7(dtc)3]Br с кластерным ядром {Mo3S7}, а также [Mo3S4(tu)8H2O]Cl4 с кластерным ядром {Mo3S4}. Получены данные о парциальном атомном составе высших занятых и свободных молекулярных орбиталей и характере взаимодействий между атомами внутри кластерного ядра.

The study of the valence state, local environment structure and magnetic properties of novel type CuCr0.99Ln0.01S2 (Ln = La, Ce) solid solutions was carried out using X-ray absorption spectroscopy, finite difference method simulations and static magnetic susceptibility measurements. The good agreement between experimental and calculated data indicates that cationic substitution does not lead to significant changes in the copper, chromium and sulfur local environment character and electronic density distribution. The copper atoms were found to be in Cu+ oxidation state, the sulfur atoms—in S2− oxidation state and the chromium atoms—in Cr3+ state. The cationic substitution of chromium by lanthanum and cerium in CuCrS2 does not significantly affect the effective magnetic moment and exchange interactions character. The lanthanum-doped CuCr0.99Ln0.01S2 solid solution demonstrates the Seebeck coefficient value 4 times greater than for CuCrS2-matrix at 500 K.

The comprehensive experimental and theoretical study of the cation-substituted disulfides CuCr0.99Ln0.01S2 (Ln=La, Ce, Gd) XANES spectra was carried out. The cationic substitution with lanthanide atoms affect to the conduction band structure was studied using the finite difference method, DFT calculations of conduction band structure and the experimental spectra interpretation. The conduction band bottom of CuCrS2 is formed mainly with the contribution of the mixed copper s-, p- and d-states, chromium d-states and sulfur p-states. After the cationic substitution the unoccupied lanthanide f-states localize near the conduction band bottom area replacing the chromium d-states. The unoccupied copper, chromium and sulfur states distribution character is preserved after cationic substitution. In the case of solid solutions CuCr1-xLaxS2 the lanthanum f−states main contribution is shifted into the high energy area from the conduction band bottom.

The monochromator of the Kosmos synchrotron radiation metrology station is discussed. The results of testing the monochromator in the energy range 2000–6000 eV using Si (111) crystals are presented. A spectral resolution ΔE/E = 10−4 was obtained. A technique for checking the spectral purity of the monochromatic radiation is described. It is shown that the monochromator can be used for spectroscopic measurements in the indicated energy range.

A set of multilayer X-ray mirrors for an upgraded version of the double-mirror monochromator installed on the VEPP-5 synchrotron of the Budker Institute of Nuclear Physics is fabricated, its constituent parts are optimized, and its X-ray optical characteristics are studied. Due to the use of seven subbands, for each of which an optimal pair of materials is chosen, the mirror set ensures high reflection coefficientsranging from 10 to 75% for a wide range of photon energies from 80 to 3000 eV and wavelengths from 0.413 to 15.48 nm. The principles of optimization of material pairs are reported. For the first time, multilayer mirrors based on the W/Be pair of materials are fabricated and studied.

The main techniques used at the COSMOS synchrotron radiation station to study the radiation hardness of semiconductor detectors are described. The spectral region around the photon energy of 100 eV is singled out from the white SR beam. A small area on the receiving detector’s surface is irradiated with a focused SR beam, and the sensitivity of the exposed and unexposed areas is investigated. The optics comprise full external reflection mirrors and thin-film filters. The techniques for calculating the surface dose are presented along with the results from measurements.