The UV photodissociation dynamics of ClO radical using velocity map ion imaging

Journal Article · Tue Nov 01 04:00:00 EST 2005 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.2083487· OSTI ID:20723191

Kim, Hahkjoon; Park, Jiho; Niday, Tracy C; North, Simon W ^[1]

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1. Department of Chemistry, Texas A and M University, P.O. Box 30012, College Station, Texas 77842 (United States)

We have studied the wavelength-dependent photodissociation dynamics of jet-cooled ClO radical from 235 to 291 nm using velocity map ion imaging. We find that Cl({sup 2}P{sub 3/2})+O({sup 1}D{sub 2}) is the dominant channel above the O({sup 1}D{sub 2}) threshold with minor contributions from the Cl({sup 2}P{sub J})+O({sup 3}P{sub J}) and Cl({sup 2}P{sub 1/2})+O({sup 1}D{sub 2}) channels. We have measured the photofragment angular distributions for each dissociation channel and find that the A {sup 2}{pi} state reached via a parallel transition carries most of the oscillator strength above the O({sup 1}D{sub 2}) threshold. The formation of O({sup 3}P{sub J}) fragments with positive anisotropy is evidence of curve crossing from the A {sup 2}{pi} state to one of several dissociative states. The curve crossing probability increases with wavelength in good agreement with previous theoretical calculations. We have directly determined the O({sup 1}D{sub 2}) threshold to be 38 050{+-}20 cm{sup -1} by measuring O({sup 1}D{sub 2}) quantum yield in the wavelength range of 260-270 nm. We also report on the predissociation dynamics of ClO below the O({sup 1}D{sub 2}) threshold. We find that the branching ratio of Cl({sup 2}P{sub 3/2})/Cl({sup 2}P{sub 1/2}) is 1.5{+-}0.1 at both 266 and 291 nm. The rotational depolarization of the anisotropy parameters of the Cl({sup 2}P{sub 3/2}) fragments provides predissociation lifetimes of 1.5{+-}0.2 ps for the 9-0 band and 1.0{+-}0.4 ps for the 8-0 band, in reasonable agreement with previous spectroscopic and theoretical studies.

• OSTI ID: 20723191
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 17 Vol. 123; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ANGULAR DISTRIBUTION
ANISOTROPY
BRANCHING RATIO
CHLORINE COMPOUNDS
DEPOLARIZATION
IONS
OSCILLATOR STRENGTHS
PHOTON-MOLECULE COLLISIONS
PREDISSOCIATION
RADICALS
ROTATIONAL STATES
WAVELENGTHS