OBSERVATION OF THE SPLITTING OF THE VIBRONIC DEGENERACY UPON ASYMMETRIC DEUTERATION OF CYCLOPENTADIENYL RADICALS

Yu, Lian; Cullin, David W.; Williamson, James M.; Miller, Terry A.

OBSERVATION OF THE SPLITTING OF THE VIBRONIC DEGENERACY UPON ASYMMETRIC DEUTERATION OF CYCLOPENTADIENYL RADICALS

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Date

1990

Authors

Publisher

Ohio State University

Abstract

Rotationally resolved electronic spectra of asymmetrically deuterated cyclopentadienyl radicals $(C p − d 1 − d 2 − d 3$ and $− d 4$ ) were recorded in a free jet expansion, Upon each deuteration, the origin band is blue-shifted by $50 c m −1$ (from $C 5 H 5 ′ s A ¯ ⟷ X ~$ origin at $29572 c m −1$ ), Asymmetric deuteration reduces the molecular symmetry from $D S h$ to $C 2 v$ , Correspondingly, the zero point level of the degenerate ground electronic state $(X ~ 2 E 1)$ splits into two non-degenerate levels, $A 2$ and $B 2$ . The order of the split levels are determined from the rotational band type. For $C p − d 1$ , it is $B 2$ above $A 2$ , whereas for $C p − d 4$ , it is $A 2$ above $B 2$ . In contrast to the symmetric $C 5 H 5$ and $C 5 D 5$ , all the rotational constants of the asymmetric molecules could be simultaneously determined. The new information and its implications on the structure and Jahn-Teller effect will be discussed.

Description

Rotationally resolved electronic spectra of asymmetrically deuterated cyclopentadienyl radicals $(C p − d 1 − d 2 − d 3$ and $− d 4$ ) were recorded in a free jet expansion, Upon each deuteration, the origin band is blue-shifted by $50 c m −1$ (from $C 5 H 5 ′ s A ¯ ⟷ X ~$ origin at $29572 c m −1$ ), Asymmetric deuteration reduces the molecular symmetry from $D S h$ to $C 2 v$ , Correspondingly, the zero point level of the degenerate ground electronic state $(X ~ 2 E 1)$ splits into two non-degenerate levels, $A 2$ and $B 2$ . The order of the split levels are determined from the rotational band type. For $C p − d 1$ , it is $B 2$ above $A 2$ , whereas for $C p − d 4$ , it is $A 2$ above $B 2$ . In contrast to the symmetric $C 5 H 5$ and $C 5 D 5$ , all the rotational constants of the asymmetric molecules could be simultaneously determined. The new information and its implications on the structure and Jahn-Teller effect will be discussed.

Author Institution: Laser Spectroscopy Facility, Department of Chemistry

URI

http://hdl.handle.net/1811/18078

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Abstracts of OSU International Symposium on Molecular Spectroscopy 1990-1999

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