Optical properties of new organic conductors based on the BEDT-TSeF molecule (the κ-(BETS)4Hg2.84Br8 superconductor and κ-(BETS)4Hg3Cl8 Metal) in the range 300–15 K

Polarized reflectance and optical conductivity spectra of single crystals of two new isostructural organic conductors based on the BEDT-TSeF molecule, namely, the κ-(BETS)₄Hg_2.84Br₈ superconductor (T _c =2 K) and the κ-(BETS)₄Hg₃Cl₈ metal, which undergoes a smooth transition to the dielectric state near 35 K, have been obtained in the spectral region 700–6500 cm⁻¹ at temperatures of 300–15 K. At 300 K, the spectra of both compounds are nearly identical and differ from the Drude spectrum characteristic of metals. The nature of the observed difference is discussed, and the spectra are described in terms of a cluster approach with inclusion of electron-electron correlations in the Hubbard approximation combined with the Drude model. The parameters of the theory were determined, including the electron transfer integrals between molecules in a cluster. The spectra in the conducting plane of the crystals were found to be essentially anisotropic, which should be assigned to specific features of in-plane interaction between molecules. The spectra of the superconductor and the metal become increasingly different as the temperature is lowered. The spectra of the metal obtained for T<150 K exhibit splitting of the broad electronic maximum in the mid-IR region into two bands, which is accompanied by a splitting of a vibronic feature deriving from electron interaction with intramolecular BETS vibrations of ν₃(A _g ) symmetry. No such splitting is observed in the superconductor spectra with decreasing temperature. __________ Translated from Fizika Tverdogo Tela, Vol. 46, No. 11, 2004, pp. 1921–1929. Original Russian Text Copyright ? 2004 by Vlasova, Drichko, Petrov, Semkin, Zhilyaeva, Lyubovskaya, Olejniczak, A. Kobayashi, H. Kobayashi.     

Structure and mechanism of the hydrolytic cleavage of o-[nitro(phenyl)acetyl] benzoic acid

Summary As a result of a study of the infrared spectra of -nitro--phenyl-acetophenone-o-carboxylic acid and its disodium salt, the structure of these two compounds was established and the cause of their different behavior in respect to hydrolytic agents was clarified.Paper 32 in the series Oxidative and Oxidative-Hydrolytic Transformations of Organic Molecules; previous papers 29–31: see [1–3].     

Method for calculating the potential of spacecraft elements in 3D space

We propose a method for calculating the potentials of the spacecraft surface, based on triangulation approximation of surfaces, the area method, and analytic calculations of the matrix elements of the Coulomb interaction. The technique described here has a wide range of applications including low, as well as geostationary and polar orbits, and increases the calculating speed and accuracy.     

Correlation functions of pure and diluted Ising magnets in the mean-field approximation

A mean-field method, which is a variant of the fixed-scale renormalization group transformation and is applied to both pure and diluted magnets, has been considered. It has been shown that, for pure magnets, the method is equivalent to the Bethe approximation. This method has been used to calculate the magnetization and correlation functions of both pure and bond-diluted Ising magnets.     

Investigation of the Potts model of a diluted magnet by local field averaging technique

Averaging of the local interatomic interaction fields has been applied to the Potts model of a diluted magnet. A self-consistent equation for the magnetization and an equation for the phase transition temperature have been derived. The temperature and magnetic atom density dependences of the spontaneous magnetization have been found for the lattices with the coordination numbers 3 and 4 and various numbers of spin states.     

Energy relations in the case of impact action on a rod

Time changes are analyzed of internal energy of a uniform free rod of constant cross section which is loaded at one end by an arbitrary time-variable force.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 96–101, July, 1972.     

Molecular conductors with differently oriented conducting layers, (EDT-TTF)3Hg2Br6 and (TMBEDT-TTF)5Hg(SCN)4-xIx

New conducting radical cation salts (EDT-TTF)₃Hg ₂Br6, (TMET) ₅Hg(SCN) _4-xI_x (x≈0.35), and (EDT-TTF)₃Hg(SCN)₃I_0.5(PhCl)_0.5 were synthesized. Their conductivities, ESR and polarized reflectance spectra were studied. It was shown that the organic conductors with differently oriented conducting layers (EDT-TTF)₃Hg₂Br₆ and (TMET)₅Hg(SCN)_4-xI_x (x≈?0.35) are characterized by the quasi-one-dimensional character of electron motion. The conductivity along and across conducting layers has a semiconductive character. It was established by ESR and polarized reflectance spectroscopy that the properties of such conductors are a superposition of the properties of individual conducting layers.     

Investigation of longitudinal vibrations of -O-H groups in chrysotile asbestos by neutron scattering and polarized infrared spectroscopy

The specific features of the vibrational spectra of chrysotile asbestos, which is a natural mineral that represents a system of closely packed tubular fibers with an outer diameter of ∼30 nm, an inside diameter of ∼5 nm, and a length up to a centimeter and more, have been investigated using neutron scattering and polarized infrared spectroscopy. This material can serve as a natural matrix for the preparation of nanostructures by filling channels with various materials.