Towards Simplified Thermal and Specific Rigidity Factors for Ion-Molecule Reactions and Ion Fragmentations

Abstract

Rate constants for capture-controlled ion-molecule reactions and ion fragmentations are analyzed. It is shown that exothermic ion-molecule reactions governed by long-range potentials (class I reactions) and ion fragmentations and the reverse ion-molecule associations with large contributions from valence potentials (class II reactions) require different treatments. The results are expressed by phase space theory and rigidity factors accounting for the anisotropy of the potentials. Thermal and specific rigidity factors, f(rigid()T) and f(rigid)(E,J) respectively. need to be internally consistent. simplified two-parameter expressions for the two rigidity factors are designed with the hope that fitting of the parameters to limited experimental data allows one to extrapolate to unexplored ranges of conditions.