Rigidity spectrum of cosmic ray variations over periods of large Forbush decreases during the 22nd and 23rd solar cycles

This work presents our findings on the rigidity spectrum of cosmic ray (CR) variations during certain Forbush decreases recorded by the global neutron monitor network in 1991–2005. In most of the events we consider, the rigidity spectrum of primary CR variations is not described by a power function of rigidity in the energy range at which the neutron monitors are most sensitive.     

On the influence of strong electric and magnetic fields on spatial dispersion and anisotropy of the optical properties of a semiconductor

Nonperturbative methods were used to construct a single-integral equation for the photon polarization operator in a semiconductor in strong electric and magnetic fields of arbitrary orientations. Spatial dispersion was taken into account. The external field configurations at which its influence could be ignored were found. Asymptotic equations for the field dependences of the absorption coefficient and refractive index were obtained. The neglect of the spin of particles was shown to lead to a fundamentally false idea of magnetic field effects on the optical properties of nonconducting crystals.     

Analysis of the local atomic structure of quantum dots of the CdS family

The microwave synthesis of quantum dots based on CdS has been performed, the temperature (T 180°C and 150°C) and synthesis duration (10 min and 5 min) have been varied. The analysis of the peak broadening in X-ray diffraction has shown that the average particle size in the synthesized samples is 10.02 nm for the CdS _{T = 180°C} sample and 5.22 nm for the CdS _{T = 150°C} sample. For both synthesis temperatures particles of sphalerite phase are formed but the sample CdS _{T = 180°C} contained some impurity of wurtzite phase too. CdK-XANES spectra in the standard samples and quantum dots have been recorded using a Rigaku R-XAS X-ray absorption laboratory spectrometer. The theoretical analysis of the CdK-XANES spectra of bulk samples of CdS and CdS nanoparticles has been performed. It has been shown that the theoretical difference spectra between bulk CdS and CdS with decreased lattice parameters demonstrate the same tendency as the experimental difference spectra between bulk CdS and the quantum dot samples under study. It has been shown that the theoretical CdK-edge HERFD-XANES spectrum in CdS demonstrates considerably more detailed structure pointed to the need of the analysis of experimental CdK-edge HERFDXANES spectra to pick out more precise information on local atomic structure parameters of small semiconducting quantum dots.     

Analysis of the atomic structure of colloidal quantum dots of the CdSe family: X-ray spectral diagnostics and computer modelling

Colloidal quantum dots of the CdSe family have been studied by X-ray absorption near edge structure (XANES) spectroscopy and computer modelling. CdK edge XANES spectra in colloidal quantum dots based on varisized CdSe nanoparticles have been recorded. Atomic structure of CdSe particles and also CdSe particles doped by transition metal atoms Mn and Co has been modelled based on the density functional theory. The embedding of the doping atoms is shown to result in considerable changes in the local atomic structure of CdSe particles. XANES spectra have been calculated above the CdK edge in CdSe particles, above the MnK edge in CdSe:Mn particles, above the CoK edge in CdSe:Co particles. The sensitivity of XANES spectroscopy to small changes in structural parameters of the nanoparticles of CdSe family has been demonstrated that furnishes an opportunity to apply it for the verification of atomic structure parameters around positions of cadmium and doping atoms of transition metals in quantum dots based on CdSe.     

<Emphasis Type="Italic">In silico</Emphasis> study of the atomic and electronic structure of quantum dots of the CdTe family doped with atoms of rare earth elements

An in silico study of semiconductor quantum dots of the CdTe family doped with atoms of rare earth elements is performed based of density functional theory. An ab initio computer design of quantum dots based on CdTe nanoparticles doped with Eu и Gd atoms is carried out. Partial densities of states of CdTe:Eu and CdTe:Gd quantum dots are calculated and analyzed. X-ray absorption near edge (XANES) spectra near the Eu K-, L₁-, and L₃- and Gd K-, L₁-, and L₃-edges of CdTe:Eu and CdTe:Gd quantum dots are calculated. The sensitivity of XANES spectroscopy for the verification of parameters of a nanosized atomic structure of quantum dots based on CdTe particles doped with atoms of rare earth elements and the determination of the local atomic structure around the atoms of rare earth elements in quantum dots is demonstrated.     

Ground level enhancement of cosmic rays on November 6, 1997: Spectra and anisotropy

Variations of the rigidity spectrum and anisotropy of cosmic rays in the period of the ground-level enhancement (GLE) of cosmic rays on November 6, 1997, according to the data from the worldwide network of ground-based stations and satellites have been studied by the unique spectrographic global survey method developed at the Institute of Solar–Terrestrial Physics, Siberian Branch, Russian Academy of Sciences. Rigidity spectra of cosmic rays in various periods of the event under study have been determined. It has been shown that the acceleration of protons in the period of this GLE event was observed to a rigidity of ~10–12 GV, and neither a power-law nor an exponential function of the rigidity of particles describes the differential rigidity spectra of cosmic rays in the event under consideration. The analysis has indicated that the Earth at the time of the GLE event was in a looplike structure of the interplanetary magnetic field.     

X-ray spectroscopic identification of garnet from the placer deposits of the Taman peninsula

Garnet from recent placer deposits of the Taman peninsula has been investigated by energy-dispersive X-ray fluorescence microanalysis and X-ray absorption near-edge structure (XANES) spectroscopy. Energy-dispersive X-ray fluorescence microanalysis showed that the chemical composition of the garnet under study corresponds to pyrope-almandine-spessartine series. The Fe K-edge X-ray absorption spectra of garnet have been recorded using a Rigaku R-XAS laboratory spectrometer. Iron K-edge XANES spectra for two iron-containing garnet minals (components), almandine and andradite, have been calculated using the full multiple-scattering and finite-difference methods. Based on a comparison of the experimental and theoretical Fe K-XANES spectra, it is concluded that recent magnetite-garnet placer deposits of the Taman peninsula contain garnet in the form of almandine.     

Wave function and the probability current distribution for a bound electron moving in a uniform magnetic field

We study the effects of electromagnetic fields on nonrelativistic charged spinning particles bound by a short-range potential. We analyze the exact solution of the Pauli equation for an electron moving in the potential field determined by the three-dimensional δ-well in the presence of a strong magnetic field. We obtain asymptotic expressions for this solution for different values of the problem parameters. In addition, we consider electron probability currents and their dependence on the magnetic field. We show that including the spin in the framework of the nonrelativistic approach allows correctly taking the effect of the magnetic field on the electric current into account. The obtained dependences of the current distribution, which is an experimentally observable quantity, can be manifested directly in scattering processes, for example.     

Nature of the electronic interactions of the NO group with the metal atom and its charge state in substituted nitroso complexes of Ru according to x-ray spectra

Institute of Inorganic Chemistry, Academy of Sciences of the USSR, Siberian Branch. Translated from Zhurnal Strukturnoi Khimii, Vol. 28, No. 5, pp. 68–72, September–October, 1987.