UNIMOLECULAR REACTION DYNAMICS OF PERSISTENT COLLISION COMPLEXES

The unimolecular decomposition of chemically activated (OCH4)dagger co mplexes, generated through collision of O(D-1(2)) with CH4 O(D-1(2)) CH4 --> (OCH4)dagger --> OH(X; upsilon < 4, N) + CH3 has been probed via polarised, Doppler-resolved laser-induced fluorescence spectroscop y of the scattered OH(X; upsilon, N). The product state-resolved diffe rential cross-sections and pair-correlated translational energy distri butions are discussed in the light of: (i) a real-time study of the re action by van Zee and Stephenson, (ii) earlier measurements of the pro duct-state distributions in OH and CH3 and (iii) the results of pair-c orrelated phase-space-theory calculations. In particular, the relation ship between 'lifetimes' and 'clock rates' is explored to provide an o verall rationale for the experimental observations on the basis of res tricted vibrational redistribution (adiabaticity) within the collision complex and the retention of some memory of its initial preparation, revealed through product-state specific opacity functions.