Mechanism for the Appearance of H+ by Electroionization of CH4. A Surprisal Analysis.

Previous experimental results on the threshold energy and on the energy range of the first wide translational energy distribution of H+, resulting from the electron impact on CH4, are interpreted. The translational energy surprisal of this distribution has been evaluated with respect to a statistically calculated one. The surprisal plot shows a fourth power dependence on fT with a negative slope associated with a large DeltaS/exc value of about 4 eu. An "a priori" calculated P(ET/E) distribution, including four constraints, fits fairly well the observed translational energy distribution.