Statistical models and NO{sub 2} photodissociation mechanism at low excess energies: Theory and experiment
- Univ. of Southern California, Los Angeles, CA (United States)
The authors have recently reported, in a preliminary communication, NO(X {sup 2}{Pi}{sub {Omega}}; v=0,1) product state distributions from NO{sub 2} photolysis in the vicinity of the NO(X {sup 2}{Pi}{sub 1/2}; v=1) + O({sup 3}P{sub J}) threshold [Robie et al., Chem. Phys. Lett., 193 (1992) 413]. The present paper extends those studies to the range of photolysis excess energies E{dagger}=0-3100 cm{sup {minus}1}. At these energies, it is reasonable to expect a high degree of vibrational predissociation from the mixed 1 {sup 2}B{sub 2}/X {sup 2}A{sub 1} NO{sub 2} electronic surface, rendering this unimolecular decay process amenable to statistical analysis. The authors examine the applicability of Phase Space Theory (PST) and microcanonical prior distributions to model the NO product state distributions from the photolysis of expansion-cooled NO{sub 2} (T{sub rot}<10 K). The NO(v=0,1) rotational distributions are found to exhibit marked fluctuations, but are well-described on average by PST and are independent of the NO spinorbit level, {Omega}=1/2, 3/2. However, the NO spin-orbit distributions are consistently {open_quotes}colder{close_quotes} than statistical, while the NO(v=0.1) are always {open_quotes}hotter{close_quotes} than predicted by either PST or prior calculations.
- OSTI ID:
- 141492
- Report Number(s):
- CONF-930304--
- Country of Publication:
- United States
- Language:
- English
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