Unimolecular Reactions and Energy Transfer of Highly Excited Molecules

Quack M and Tree J 1976 Unimolecular reactions and energy transfer of highly excited molecules Gas Kinetics and Energy Transfer mo 2, oh 5, ed P G Ashmore and R J Donovan (London The Chemical Society) pp 175-238 (a review of the literature published up to early 1976)... 

Unimolecular Reactions and Energy Transfer of Highly Excited Molecules... 

Quack, M., Troe, J. Unimolecular Reactions and Energy Transfer of Highly Excited Molecules. Specialist Periodical Reports. London The Chemical Society, 1977, pp. 175 -238. 

Step 1 is the unimolecular decomposition of a diatomic molecule, and step —1 is a recombination of two atoms. This recombination is a highly exothermic reaction, and this energy will reside in the newly formed bond, which is thus highly excited. If this energy is not removed in the time of one vibration, the molecule will split up on vibration and recombination will not occur. If a collision occurs before the first vibration, then energy transfer takes place and the bond will be stabilized. The third body fulfils this function. This is more effective at high pressures and low temperatures. 

Collisions of highly vibrationally excited molecules is eommonly a topie in the field of unimolecular reactions [1,2,3,4,5]. Collisions of vibrationally excited moleeules in that field are studied in the context of energy transfer, namely, when nonreaetive but inelastic collisions change the energy content of the moleeule that may undergo a unimolecular reaction. The possibility that the collisions of the exeited moleeules in the gas phase with reactive partners ean show specific phenomena has traditionally not been considered, exeept for diatomie moleeules. Bimolecular reaetions of vibrationally exeited moleeules have beeome a subjeet of intense study reeently, when experimental work indieated that a remarkable speed-up and state speeifieity ean be observed when simple moleeules in vibrationally exeited states collide with reactive partners [6,7,8, 9]. 

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