sd-Exchange electron spin resonance in a ferromagnetic metal

The possibility of resonance absorption in the terahertz range caused by the sd-exchange interaction at the incidence of an electromagnetic wave on a ferromagnetic metal has been predicted. The absorption coefficient has been calculated. It has been shown that the resonance frequency is determined by the magnetization of a ferromagnet and the absorption coefficient additionally depends on the orientation of the magnetization with respect to the plane of polarization of the wave.     

Collisional activation of ions in RF ion traps and ion guides: The effective ion temperature treatment

Ion transfer and storage using inhomogeneous radio frequency (RF) electric fields in combination with gas-assisted ion cooling and focusing constitutes one of the basic techniques in mass spectrometry today. The RF motion of ions in the bath gas environment involves a large number of ion-neutral collisions that leads to the internal activation of ions and their effective "heating" (when a thermal distribution of internal energies results). The degree of ion activation required in various applications may range from a minimum level (e.g., slightly raising the average internal energy) to an intense level resulting in ion fragmentation. Several research groups proposed using the effective temperature as a measure of ion activation under conditions of multiple ion-neutral collisions. Here we present approximate relationships for the effective ion temperature relevant to typical operation modes of RF multipole devices. We show that RF ion activation results in near-thermal energies for ions occupying an equilibrium position at the center of an RF trap, whereas increased ion activation can be produced by shifting ions off-center, e.g., by means of an external DC electric field. The ion dissociation in the linear quadrupole ion trap using the dipolar DC ion activation has been observed experimentally and interpreted in terms of the effective ion temperature.     

Electron-diffraction investigation of the structure of o-bromonitrobenzene,m-bromonitrobenzene,and 2,6-dinitrobromobenzene molecules in the gas phase

M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 29, No. 4, pp. 53–63, July–August, 1988.     

Geometric structure of molecule of N-nitropyrrolidine in the gas phase

M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 46–50, January–February, 1992.     

Geometric structure of molecule of 1,3-dinitro-1,3-diazacyclopentane in the gas phase

M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 33, No. 1, pp. 35–40, January–February, 1992.     

Introduction

Structural Chemistry -     

Vibrational spectra and rotational isomerism of bis(N-2-chloroethyl)nitramine

The IR and Raman spectra of bis(N-2-chloroethyl)nitramine (BCENA) in the liquid and crystalline states and in CCl₄ and CH₃CN solutions are studied. The spectra are compared, and it is concluded that BCENA exists as a mixture of conformers of different polarities in the liquid state and as one less polar conformer in the crystalline state. To determine the conformations corresponding to the total electron energy minima and interpret the vibrational spectrum of BCENA, we performed an ab initio quantum chemical calculation of the BCENA molecule in the Hartree-Fock approximation using the 3–21G* and 6–31G* basis sets. Out of twelve possible conformations five are stable; the most stable conformer is C₂(GG). The frequencies and forms of normal vibrations of stable conformers are calculated using scaled quantum chemical force fields. The calculated and experimental frequencies are compared, and the relations between the frequencies of skeletal stretching and bending vibrations are analyzed. It is concluded that the BCENA crystal is formed by the C₂ (GG) conformer. The vibrational spectrum is interpreted, and the frequencies are assigned to vibrations of conformers differing in form. Translated fromZhumal Struktumoi Khimii, Vol. 38, No. 2, pp. 303–317, March–April, 1997.     

Electron-diffraction investigation of the structure of the 2-methyl-5-vinyltetrazole molecule in the gaseous phase

M. V. Lomonosov Moscow State University. Translated from Zhurnal Strukturnoi Khimii, Vol. 30, No. 2, pp. 56–63, March–April, 1989.