Momentum transfer theory of ion transport under the influence of resonant charge transfer collisions: the case of argon and neon ions in parent gases

Transport properties of ion swarms in presence of Resonant Charge Transfer (RCT) collisions are studied using Momentum Transfer Theory (MTT). It was shown that, not surprisingly, RCT collisions may be represented as a special case of elastic scattering. Using the developed MTT we tested a previously available anisotropic set of cross-sections for Ar+Ar ⁺ collisions by making the comparisons with the available data for the transverse diffusion coefficient. We also developed an anisotropic set of Ne+Ne ⁺ integral cross-sections based on the available data for mobility, longitudinal and transverse diffusion. Anisotropic sets of cross-sections are needed for Monte Carlo simulations of ion transport and plasma models. Received 16 June 2002 / Received in final form 2nd August 2002 Published online 24 September 2002 RID="a" ID="a"e-mail: vrhovac@phy.bg.ac.yu RID="b" ID="b"e-mail: zoran@phy.bg.ac.yu     

On the steady-state solutions of the kinetics of homogeneous nucleation

A general solution to the steady-state equations for the kinetics of homogeneous nucleation is determined, in agreement with irreversible thermodynamics. Most of the steady-state distributions of clusters present a minimum. Our theory provides a conjecture for understanding the apparent contradictions existing in the present experimental data.     

Synthesis and characterization of new complexes between sodium monoalkyl benzeneazophosphonates and dibenzo-18-crown-6

A new series of crystalline complexes of sodium monoethyl ester and sodium monobutyl ester of [α-(4-benzeneazoanilino)-N-benzyl]phosphonic acid,     

Excessive hydrogen and deuterium Balmer lines broadening in a hollow cathode glow discharges

Results of a Doppler spectroscopy study of hydrogen and deuterium Balmer lines in the stainless steel and copper hollow cathode glow discharge, operated in pure hydrogen, deuterium and mixtures of inert gases with hydrogen, are reported. For all gases and gas mixtures plasma observations perpendicular to electric field revealed the excessively large Doppler broadening. By changing mode of glow discharge operation, the Doppler broadened line profiles in helium-hydrogen mixture are recorded parallel to the discharge electric field as well. The excessively broadened part of the H line profile is shifted towards blue or red wavelength by changing the direction of electric field vector. The presence of large excessive Balmer lines broadening in pure hydrogen and in its gas mixture with neon as well as shifting of the excessively broadened part of line profile by means of electric field is in contradiction with the resonance transfer model proposed by Mills et al. in several publications, see e.g. [IEEE Trans. Plasma Sci. 31, 338 (2003)].     

Modulational instability on triangular dynamical lattices with long-range interactions and dispersion

The influence of long-range interactions on the stability of stationary solutions of triangular lattices described by the continuum-discrete nonlinear Schrödinger equation is analyzed. By virtue of the linear stability analysis and a variational approach we demonstrate that both soliton array and continuous-wave solutions are modulationally unstable. Analytical expressions for instability thresholds and growth rate spectra are presented and compared with the corresponding results in the approximation of a nearest neighbor interaction.     

Data and modeling of negative ion transport in gases of interest for production of integrated circuits and nanotechnologies

We review techniques to prepare, evaluate and apply sets of cross section and transport data for negative ions that are required for the modeling of collisional non-equilibrium plasmas used for processing of microelectronic circuits. We collect and discuss the transport coefficients and cross section sets.We have compiled data for negative ions in CF₄ and CF₄-related negative ions in rare gases. In addition, we consider data for F⁻ and CF₃⁻ in rare gases. Furthermore, we analyze the cross sections of halogen negative ions in rare gases and other molecules. This is followed by the data for SF₆ related ions in SF₆ and in rare gases. The cross section for scattering of O⁻ in O₂ has been derived from the transport data and used to make calculations of the transport properties. Finally we give a brief discussion of the availability of the data for H⁻ ions in H₂. We have derived cross sections in several cases but the basic aim is to show the basic features of transport coefficients. In particular we discuss the need to represent properly some details such as the non-conservative nature of transport coefficients and the anisotropy of diffusion. Application of approximate theories and representations of cross sections are also discussed.     

Determination of diphenylamine and its mono-derivatives in single-base gun propellants during aging by high performance liquid chromatography

Summary The separation and quantitative determination of diphenylamine and its mono-derivatives in single-base gun propellants during aging was investigated by High Performance Liquid Chromatography (HPLC). We have defined optimal conditions to allow determination of diphenylamine and its mono-derivatives during aging until their levels fell below limits of detection. These compounds were determined in a single-base gun propellant during a storage period of 168 hours at 100°C using a developed, successfully verified HPLC method.     

Characterization of polypropylene/layered silicate nanocomposites prepared by single-step method

The extent of organo-modified clay (C93A) platelets dispersion in polymer matrix and crystallization and melting behavior of iPP-based nanocomposites prepared by a single-step melt-mixing method were investigated by wide-angle X-ray diffraction (WAXD), transmission (TEM), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). WAXD patterns revealed exfoliated structure of nanocomposites containing 1 wt% clay, and mixed intercalated/exfoliated structure at higher concentration of nanoclay. The isothermal crystallization proceeds faster in the matrix polymer (iPP/PP-g-MA) than in nanocomposite samples. The results obtained for T _m ^o suggest that the presence of nanoclay has induced a perfection of the formed crystals. The presence of C93A particles in PP leads to increase in crystallization peak temperature implying nucleating ability of clay particles, which was more pronounced in exfoliated than in mixed intercalated/exfoliated system.     

Composite layers consisting of polyaniline and poly(o-phenylenediamine): Electrochemical deposition, electrochromic and electrocatalytic properties

The composite polymer layers consisting of polyaniline (PANI) and poly(o-phenylenediamine) (poly(o-PDA)) were electrodeposited on a platinum electrode by simultaneous electrochemical oxidation of corresponding monomers from aquaeous hydrochloric solutions. The growth of PANI and poly(o-PDA) occurs separately resulting in layers with two distinct, finely distributed phases. The first deposited layers are composed mainly of poly(o-PDA) and become richer in PANI as the electropolymerization proceeds. The aniline/o-PDA copolymer was not formed during electrodeposition, as evidenced by cyclic voltammetry and Fourier-transformed IR spectroscopy. It was demonstrated that the electrochromic properties of resulting composite layers are the combination of yellow/brown-reddish and green/dark blue observable color transitions which are characteristics of poly(o-PDA) and PANI, respectively. Electrocatalytic properties of the electrosynthesized composite layers were investigated on quinone/hydroquinone (Q/H₂Q) redox system and it was shown that the composite layers increase the heterogeneous electron transfer rate with a magnitudes ranging from those obtained on pure poly(o-PDA) to those obtained on pure PANI layer.