On the preference for vibrational energy in diatomic dissociation

✍ Scribed by J.H. Kiefer; H.P.G. Joosten; W.D. Breshears

• Publisher: Elsevier Science
• Year: 1975
• Tongue: English
• Weight: 627 KB
• Volume: 30
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(75)80023-6

✦ Synopsis

Recent measure&nts bf &so&ion

and r&&ion rates, a,nd of di&cti~on induction'timcs, are shown to indicate .. wry serious depfetion of vibrational state popuktiqns durir?g therma! dissociation. The large measured dissociation rates az-rc then or& compatible with d&so&&on from low vibrational states; i.e., there can bc at most a veti weak bias favoring vibrational excitation in thermal dissociation. It is sumsted that dissoc%tion from low.vibrational states is assisted by rotational excitation.

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1. hltroduciiorl %, --. '.

In nearly all of the numeious theories of thermal diatdmic association [ 1,2] *, vibrational energy of t& dissociating molecule makes by far the dominant contribution to the requisite energy. Dissociation takes'place from high vibtitibna! states-which are but slightly"depleted in the prbcess. Here we show -+hat recent measurements of re&afion and clissocia-'&o&are noi consistent ;vith jhis~mechanism. These results indicate that depletion is actually quite severe and ttit dissociation must take place to an appreciable extent from lq& ~br~tion~ states, in accord ,' with th6 early ideas of Careri [3] and the recent theory bf idhnston a& Birks [2].