Surface reaction kinetics unimolecular decomposition

A stable ion structure is one which corresponds to a local minimum on a potential energy surface of an ion. It is implied that a stable ion structure in its ground vibronic state is stable with respect to unimol-ecular reaction. A great deal is known of the possible stable ion structures of particular formulae [54, 401, 517, 595]. The relevance of stable ion structures to reaction kinetics is, of course, that it is their vibrationally excited states which are assumed to be the reactants (and products) in the unimolecular decompositions and isomerisations. Identifying stable ion structures is an essential prerequisite to determining energies (heats)... 

Gas phase kinetic results (Table 64) on hydroperoxide decompositions (methyl, ethyl, isopropyl and t-butyl hydroperoxide) are very poor. Since the thermochemistry is fairly well established for these reactions, and since observed activation energies are as much as 6 kcal.mole lower than the reaction enthalpies, it is apparent that the reported parameters cannot be those for the unimolecular hydro-peroxy bond fission processes. Surface catalysis was considerable in all experimental systems. It therefore seems likely that the true homogeneous reactions were never completely isolated. 

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