Fast and Slow Diffusion of Channelized Particles in Transverse Energy Space

The Fokker–Planck-type kinetic equation is constructed with the help of the evolution equation for the transverse energy of channelized particles, which in its turn is derived beyond the framework of perturbation theory proceeding from the condition of nonconcervation of the adiabatic invariant.     

Role of phosphates in the promotion of silver catalysts for partial oxidation: I. Structure and properties of phosphates on the surface of polycrystalline silver

The chemical composition, structure, and properties of an H₃PO₄-promoted polycrystalline silver foil are studied by XPS. The surface of the doped sample contains oxygen in two states with binding energies of 531.1 and 533.0 eV. Heat treatment results in silver clusters distributed in the polyphosphate matrix. It follows from TDS data that the surface of the promoted catalyst contains a strongly bound oxygen species that desorbs at ~900 K. It is believed that the silver clusters stabilized by the phosphate matrix are active sites on the surface of the phosphorus-promoted catalyst.Translated from Kinetika i Kataliz, Vol. 46, No. 1, 2005, pp. 153–160. Original Russian Text Copyright © 2005 by Knyazev, Boronin, Vodyankina, Koshcheev, Kurina.     

Surface State of a Silver Catalyst for Ethylene Glycol Oxidation

The surface state of electrolytic silver before and after treatment with a reaction mixture in the course of ethylene glycol oxidation to glyoxal was studied using X-ray photoelectron spectroscopy and scanning electron microscopy. It was found that electrophilic forms of adsorbed oxygen, which participate in the selective conversion of ethylene glycol, were formed on the surface of electrolytic silver crystals under exposure to oxygen under conditions similar to catalytic process conditions. The treatment of the catalyst with a reaction mixture resulted in the formation of filamentous carbon deposition products. A mechanism of formation of carbon-containing products was proposed.     

Modeling the photoelectron spectra of the valence O2p-band of zinc oxide by the Xα-scattered wave method

The photoelectron spectra (PES) of the valence O2p-band of zinc oxide are modeled by Xα-scattered wave cluster calculations in a wide range of incident quantum energies hv (from 30 to 150 eV and 1253.6 eV). For the Zn₁₀O₁₀ cluster, the calculated intensities of PES reproduce well the specific features of the experimental spectra. It is shown that Zn3d-electrons participate in covalent binding of zinc and oxygen. The admixture of the Zn3d-states in the hybrid orbitals of the valence band is ≈7%. Deceased. Translated fromZhurnal Struktumoi Khimii, Vol. 38, No. 5, pp. 877–886, September-October, 1997.     

Grounds for the application of fractional-order diffusion equations in channeling theory using the Langevin approach

Transverse-energy distribution densities in the case of ultrarelativistic proton channeling in the (100) planes of diamond-like crystals have been numerically calculated within the framework of the Langevin approach. Based on the self-similarity principle, the subdiffusion character of the motion under consideration has been established, which can be regarded as grounds for using fractional-order diffusion equations to adequately describe channeling and dechanneling processes mathematically.     

Transverse energy distribution of channeled particles in a thin crystal

In this paper we consider a chain of approximate equations of motion describing the effect of planar channeling of protons and antiprotons in transverse energy space. The original nonlinear stochastic equation of motion is linearized with the help of expansion in a series with respect to a small parameter, the role of which is played by the fluctuation of the transverse force. We have done a numerical study of the transverse energy redistribution of the proton and antiproton flux in the (110) planar channel of a thin silicon crystal. We show that the transverse energy distribution function is the same for protons and antiprotons when the angles of incidence are larger than the two critical channeling angles. Surgut State University. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 9–12, September, 1997.     

Formation Mechanism and Structure of Monatomic Carbon Films in Ethylene Decomposition on the Pt(111) Surface According to XPS Data

The interaction of ethylene with a Pt(111) single-crystal surface was studied using X-ray photoelectron spectroscopy. It was found that both two-dimensional flat graphite islands and curved fullerene-like carbon structures or nanotubes can be formed depending on the reaction temperature of ethylene and the presence of dissolved carbon in the bulk of the crystal. It was assumed that the size and curvature of the islands depend on the size of terraces on the single-crystal surface.     

Decompositions of metrizable compact spaces admittingT-systems of complex-valued functions

Upper semicontinuous decompositions into continua of a metrizable compact space admitting a Chebyshev system of continuous complex-valued functions are considered. It is proved that the cyclic elements of the Moore decomposition space can be embedded in the two-dimensional sphere. Translated fromMatematicheskie Zametki, Vol. 62, No. 2, pp. 259–267, August, 1997. Translated by O. V. Sipacheva