Surprisal analysis of products' translational energy distribution in molecular collisions

Experimental and trajectory-generated products' translational energy distributions are shown to be well represented by expressing ω(E′_T) = P(E′_T/P⁰(E′_T) as a gaussian in the final momentum. (A quadratic surprisal plot.) It is also verified that the entropy deficiency of the actual distributions is quite close to the minimal value of the entropy deficiency (subject to the constraints). The dependence of the product E′_T distribution on the translational energy of the reagents is found to be simple. Microscopic reversibility is employed to study this point and to relate the surprisal parameters of the forward and reversed reactions. The physical interpretation of the results for direct reactions in terms of a 'Franck-Condon'-like momentum transfer constraint is discussed.