Estimates Of Rate Coefficients Research Articles

Noble gas halide ions: KrCl+, KrF+, ArCl+, ArI+

Noble gas halide ions are observed mass spectrometrically in low-pressure discharges of noble gas halide mixtures like Kr+Cl2 and Ar+Cl2. Under similar discharge conditions, KrCl+ forms more readily than ArCl+. The most probable process of producing KrCl+ is three-body association of Kr to Cl+ with an estimated rate coefficient of 4×10−28cm6s−1. ArCl+ cannot be formed in this way because the recombination energy of Cl+ is too low by ≳1 eV. KrF+ is observed weakly in Kr+CF4 or Kr+SF6 mixtures. ArI+ can only be observed when Ar+I2 mixtures are traversed by accelerated electrons and the ArI+ ions are not allowed to collide with neutrals or electrons. A negative peak of mass number 59 observed in Ar+CF4 could be ArF−, but is probably an impurity like C2OF−.

The physics of electron beam excited rare gases at high densities

The unique properties of charged particle excited high density rare gases are reviewed in terms of the basic collisional and radiative processes upon which they depend. Both low and high excitation density conditions are considered and a kinetic model of the important processes is formulated using available and estimated rate coefficients.

A quasiclassical trajectory study of the H2+F2 reactions

A theoretical investigation of the reaction dynamics of the reactions H2(v=0,2,4, or 6) + F2(v=0 or 6) → H+HF+F, 2HF, F2H+H, H2F+F, F2+2H, and H2+2F has been accomplished using Monte Carlo averaging over quasiclassical trajectories on a reasonable semiempirical potential-energy surface. The details of the dynamical mechanism of the reaction processes were investigated by examining geometrically restricted reaction paths and selected restricted initial states. Reaction cross sections have been computed and estimates of rate coefficients have been made. The computed thermal rates are many orders of magnitude lower than thermal collision frequencies. Reaction thresholds are lowered significantly for vibrationally excited hydrogen.

Estimation of rate coefficients from pulsed microcatalytic reactors: Oxidation of ethylene over silver catalyst

The experimental conditions and requirements for the continuity equation to reduce to a total differential equation are analyzed. These lead to a simple method for obtaining rate coefficients from pulsed microcatalytic reactors, provided that the conversions are limited to differential conversions. Coefficients obtained this way, for ethylene oxidation over silver, are compared with estimations from steady state data.