Quantum mechanical expressions for the pressure-dependent recombination rate (within the strong collision assumption) are presented which have a very similar form to those developed recently for rate constants of chemical reactions : eqs 11 and 12 express the recombination rate in terms of a flux autocorrelation function, and eqs 14-16 in terms of a cumulative recombination probability. The qualitative behavior of these functions is illustrated by several pedagogical examples.