Surprisal analysis and probability matrices for rotational energy transfer

Abstract
The information‐theoretic approach is applied to the analysis of state‐to‐state rotational energy transfer cross sections. The rotational surprisal is evaluated in the usual way, in terms of the deviance of the cross sections from their reference (’’prior’’) values. The surprisal is found to be an essentially linear function of the energy transferred. This behavior accounts for the experimentally observed exponential gap law for the hydrogen halide systems. The data base here analyzed (taken from the literature) is largely computational in origin: quantal calculations for the hydrogenic systems H2+H, He, Li+; HD+He; D2+H and for the N2+Ar system; and classical trajectory results for H2+Li+; D2+Li+ and N2+Ar. The surprisal analysis not only serves to compact a large body of data but also aids in the interpretation of the results. A single surprisal parameter ϑR suffices to account for the (relative) magnitude of all state‐to‐state inelastic cross sections at a given energy.