Mass spectrometry of molecules and radicals in glow discharge plasma

The article represents a method and equipment developed for mass spectrometric analysis of plasma, that is, for measurement of concentration of atoms and molecules, and their fragments, including free radicals. A compact and inexpensive mass spectrometer is based on a quadrupole residual gas analyzer (RGA-200, Stanford Research Systems). The design of the two-section differential pumping chamber makes it possible to bring the mass-spectrometer analyzer to the entrance diaphragm to a distance of 40 mm in order to measure quick reacting and easily condensed particles. The equipment was used for analyzing the composition of spherical glow discharge plasma in methanol vapor and acetone-nitrogen mixture. A procedure for mass spectrum processing is proposed. Time-varying concentrations of all observed neutral particles are measured. Presently available data on sections of complete and dissociative ionization of molecules and their fragments, which are necessary for reconstructing concentrations of particles in plasma from measured mass spectra, are presented.     

On the Gomory–Hu Inequality

It was proved by R. Gomory and T. Hu in 1961 that, for every finite nonempty ultrametric space (X, d), the inequaliy \( \left| {\mathrm{Sp}(X)} \right|\leq \left| X \right|-1 \), where Sp(X) = {d(x, y) : x, y ∈ X, x ≠ y} , holds. We characterize the spaces X for which the equality is attained by the structural properties of some graphs and show that the set of isometric types of such X is dense in the Gromov–Hausdorff space of the isometric types of compact ultrametric spaces.     

AC Josephson effect in the long voltage-biased SINIS junction

Theory of non-stationary coherent effects is developed for superconductor-normal-superconductor (SNS) structures with relatively strong normal scattering on S/N interfaces (interface resistance is large compared to intrinsic resistance of N metal). Analytical expressions are found for the time-dependent anomalous Green’s functions induced in the N region under the fixed-voltage-bias. The amplitude of the current oscillations is determined in non-equilibrium conditions. Non-stationary correction to the distribution function is calculated in high-temperature limit and found to be slowly decreasing with the temperature, leading to the dominance of the second-harmonic term in the Josephson current, I _s (t) ∝ sin(4eVt) at high temperatures and low voltage. The article is published in the original.     

Photoelectron spectra and electronic structure of boron difluoride β-diketonates with aromatic substituents

The electronic structure of boron difluoride chelate complexes of the acetyl acetonate type containing 4-biphenylene, 2-fluorene and 4-trans-stilbene as β-substituents is studied by means of photoelectron spectroscopy and quantum chemistry in the DFT approximation. It is established that the substituents affect the nature and sequence of the spectral bands. It is shown that calculation results corrected to the value of the Koopmans defect reproduce quite well the energy intervals between ionized states of complexes.     

Spectroscopy of output pressure dependences of water vapor passed through adsorbent

The output concentration pressure dependences of the water vapor passed in portions through a layer of MN-200 adsorbent whose delay and shape drastically depend on the parameters of introduced portions are determined using diode-laser spectroscopy. A model describing the experimental data and demonstrating the important role of interphase mass-exchange lag in the process of water vapor propagation in a porous-granular medium is proposed.     

Effect of the polymer matrix on the efficiency of emission of laser dyes

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 52, No. 4, pp. 554–560, April, 1990.     

One-pot synthesis of substituted styrenes from vicinal dibromoalkanes and arylboronic acids

Dehydrobromination of vicinal dibromoalkanes in systems comprising 1,2-dimethoxy-ethane, N-butyl-N′-methylimidazolium tetrafluoroborate (or tetrabutylammonium bromide), and a base with subsequent palladium-catalyzed cross-coupling of the thus formed bromoalkenes with arylboronic acids furnished substituted styrenes. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 116–123, January, 2007.