ISSN:
1432-2234
Keywords:
Boltzmann equation
;
Dipole moment
;
Gases
;
Ions
;
Reaction kinetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Using the Fokker-Planck version of an approximate Boltzmann equation for the ion (translational) energy distribution function f I the departure, Δk, of the non-equilibrium ion-(polar) molecule reaction rate coefficient k non from its equilibrium value k (eq) is calculated. Δk enhances considerably with an increase of the dipole moment of the reacting molecular species (“locked dipole” reaction model). But the Δk-values, e.g. for reactions of H−(D−) and nitromethane in xenon enhance also with increasing ratio ϱ of the concentrations of CH3NO2 and Xe and decrease with enhancing gas temperature T. The reaction-induced (translational) non-equilibrium effect leads to a (non-equilibrium) kinetic isotope effect depending on ϱ and T. At T=300 K the example yields k H /k d =1.345(ϱ=5 · 10−4),=1.409 (ϱ=10−5) and=1.414−k H /(eq) /k D (eq) (ϱ≤10−6).
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00540029
