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Formation of a long‐lived collision complex in alkali diatomic–rare gas collisions and rotational excitation via a mode‐specific dissociation

Bain, AJ; (1985) Formation of a long‐lived collision complex in alkali diatomic–rare gas collisions and rotational excitation via a mode‐specific dissociation. Journal of Chemical Physics , 82 (3) pp. 1298-1307. 10.1063/1.448452. Green open access

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Abstract

We report an unusual pressure dependence of the gas phase dynamics of alkali diatomics in 1Π excited states in their interactions with certain collision partners. This behavior consists of a change in the relative rates of the ΔJ=+1 and ΔJ=−1 collision‐induced transitions, which results in a dominance of rotational excitation at high pressures. This effect occurs only for the e Λ‐doublet component of the excited 1Π 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 Λ 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.

Type: Article
Title: Formation of a long‐lived collision complex in alkali diatomic–rare gas collisions and rotational excitation via a mode‐specific dissociation
Open access status: An open access version is available from UCL Discovery
DOI: 10.1063/1.448452
Publisher version: http://dx.doi.org/10.1063/1.448452
Language: English
Additional information: The following article appeared in: Bain, AJ; (1985) Formation of a long‐lived collision complex in alkali diatomic–rare gas collisions and rotational excitation via a mode‐specific dissociation. Journal of Chemical Physics, 82 (3) pp. 1298-1307, and may be found at: http://dx.doi.org/10.1063/1.448452. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
Keywords: Excited states, Polarization, Dissociation, Gas dynamics, High pressure
UCL classification: UCL
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UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/1400111
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