Formation of a long-lived collision complex in alkali diatomic--rare gas collisions and rotational excitation via a mode-specific dissociation
Journal Article
·
· J. Chem. Phys.; (United States)
We report an unusual pressure dependence of the gas phase dynamics of alkali diatomics in /sup 1/Pi excited states in their interactions with certain collision partners. This behavior consists of a change in the relative rates of the ..delta..J = +1 and ..delta..J = -1 collision-induced transitions, which results in a dominance of rotational excitation at high pressures. This effect occurs only for the e ..lambda..-doublet component of the excited /sup 1/Pi state. Also observed is a change in the polarization of the parent line such that the polarization ratio increases with increasing pressure. The dependence of this behavior on intermolecular potential, reduced duration of collision, rotational state, and temperature lead us to propose that a long-lived complex or orbiting resonance is responsible for the effects observed. This species appears to be formed during the lifetime of the excited state of the diatomic. Knowledge of the molecule-fixed geometry of the ..lambda.. doublets allows us to propose a structure for the long-lived species and to speculate that the observed characteristic rotational excitation results from specific vibrational and rotational predissociation processes within the complex.
- Research Organization:
- School of Chemistry and Molecular Sciences, University of Sussex, Falmer, Brighton BN1 9QJ, United Kingdom
- OSTI ID:
- 6262475
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 82:3; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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