Cross Sections and Rate Coefficients for O⁺ Reacting With N₂, O₂, and NO

Abstract

Ion‐molecule reaction cross sections between 0.03 and 3 eV can best be inferred from data taken in drift tube mass spectrometers. For the title reactions, the cross sections inferred from drift‐tube measurements in the late 1970s have been accepted as accurate, even though the methods used to infer them made substantial assumptions about the ion velocity distribution functions. Here the Gram‐Charlier method for solving the Boltzmann equation is used to obtain ion distribution functions that are anisotropic, having different average energies parallel and perpendicular to the uniform electrostatic field. The Gram‐Charlier method incorporates skewness, kurtosis, and correlation between the motions parallel and perpendicular to the field. This leads to more accurate ion distribution functions from which more accurate reaction cross sections have been inferred. The results differ by as much as 50% from the generally accepted cross sections that are currently used to model ion‐neutral reactions in the upper atmosphere.

Third-order transport coefficients for electrons in N2 and CF4: effects of non-conservative collisions, concurrence with diffusion coefficients and contribution to the spatial profile of the swarm

“…Transport coefficients of third and higher order have been implemented to analyse ion swarm experiments [51][52][53][54][55]. However, they have been almost systematically ignored in the traditional analysis of electron swarm experiments, as they are difficult to measure and difficult to study by employing theoretical methods [56][57][58].…”