Ion-Molecule Association Reactions

The overall reaction for the general ion-molecule association process is (1)$${A^ + } + B\xrightarrow{{{k_2}}}A{B^ + }$$ where k₂ is the second-order rate constant for formation of the association product AB. In this paper we will deal with association reactions which proceed through the formation of a long-lived excited intermediate complex according to the mechanism where k_f, k_b, k_s, k_r and k_d represent the rate constants for formation of the excited complex, back-dissociation of the complex, stabilization of the complex via collisions with bath gas M, stabilization of the complex via radiative emission of a photon, and dissociation of the complex into some fragment channel other than the reactant channel. Note that the incorporation of more than one such channel into mechanism 2 will not be discussed here, but is straight-forward. For each of the specific systems which will be discussed here either k_r or k_d or both will be zero.