Translational Energy Disposal and Mechanisms of Unimolecular Dissociative Photoionization with He(I) and Ne(I) Resonance Lines. A Surprisal Ananlysis of the CH3F->CH3++F Process.

The He(I) and Ne(I) photoions translational energy spectra of CH3+ from CH3F were measured. At both wavelengths, the translational energy spectrum is made of two components. Their surpisal analysis shows two distinct behaviours: (i) the low energetic and narrow component exhibits a positive slope, whereas (ii) the high energetic and widely spread component is characterized by a negative slope. Furthermore, when He(I) is used, the high translational energy distribution shows a multimodal surprisal. These observations as well as the origin of both distributions are discussed.