Vibrational energy flow distributions

It is also worth noting that the equivalence [317], which exists for thermal systems in terms of level of approximation and assumption between the RRKM and Slater [772] approaches, is lost in mass spectrometry. To adopt the Slater position that there is no energy flow among modes, immediately demands further information, and almost certainly further assumptions, since the form of the initial distribution of vibrational (and electronic) energy is a specific property of the ion dependent upon the ionization process. 

One interesting conclusion that can be drawn from the work with hot molecules relates to the problem of energy flow between normal modes. If there were little energy flow it would be expected that a hot molecule of methylcyclopropane produced from CH2 and cyclopropane would show different behaviour from one made from CH2 and propene, since the energy would be distributed differently in the two cases. No difference in kinetic behaviour is detected, however, in this and similar systems, and this indicates that there is rapid flow of energy between the modes of vibration. 

The short-time spike in the decay, which can be attributed to the dephasing of many quantum beat terms (all with + 1 phases), represents the irreversible flow of vibrational energy out of the zero-order state prepared by the laser. The long-time component, although weakly modulated, represents an equilibration in the distribution of vibrational energy subsequent to the initial energy flow process. 

Initial vibrational distributions for HF(v) and DF(v) were measured for v = 1 to 4 and were shown to be independent of the NF2 flow rate. Occupation of the v = 5 state was observed for neither HF nor DF. Experimental distributions, P, were used to extrapolate the occupation of the v = 0 state either from a linear log Pv vs. Ev correlation (E vibrational energy) or from a surprisal analysis. Resulting distributions are given below together with (E) (the mean energy being available for the NF(a) path, (E) = AHo+Ea (assumed 1 kcal/mol) + V2 RT) and energy fractions stored in vibration, (f ), and rotation (f ) [26] ... 

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