A photodissociation study of CH{sub 2}BrCl in the A-band using the time-sliced ion velocity imaging method
- Department of Chemistry, University of California, Davis, One Shields Avenue, Davis, California 95616 (United States)
Employing a high-resolution (velocity resolution {delta}{nu}/{nu}<1.5%) time-sliced ion velocity imaging apparatus, we have examined the photodissociation of CH{sub 2}BrCl in the photon energy range of 448.6-618.5 kJ/mol (193.3-266.6 nm). Precise translational and angular distributions for the dominant Br({sup 2}P{sub 3/2}) and Br({sup 2}P{sub 1/2}) channels have been determined from the ion images observed for Br({sup 2}P{sub 3/2}) and Br({sup 2}P{sub 1/2}). In confirmation with the previous studies, the kinetic-energy distributions for the Br({sup 2}P{sub 1/2}) channel are found to fit well with one Gaussian function, whereas the kinetic- energy distributions for the Br({sup 2}P{sub 3/2}) channel exhibit bimodal structures and can be decomposed into a slow and a fast Gaussian component. The observed kinetic-energy distributions are consistent with the conclusion that the formation of the Br({sup 2}P{sub 3/2}) and Br({sup 2}P{sub 1/2}) channels takes place on a repulsive potential-energy surface, resulting in a significant fraction (0.40-0.47) of available energy to appear as translational energy for the photofragments. On the basis of the detailed kinetic-energy distributions and anisotropy parameters obtained in the present study, together with the specific features and relative absorption cross sections of the excited 2A{sup '}, 1A{sup ''}, 3A{sup '}, 4A{sup '}, and 2A{sup ''} states estimated in previous studies, we have rationalized the dissociation pathways of CH{sub 2}BrCl in the A-band, leading to the formation of the Br({sup 2}P{sub 3/2}) and Br({sup 2}P{sub 1/2}) channels. The analysis of the ion images observed at 235 nm for Cl({sup 2}P{sub 3/2,1/2}) provides strong evidence that the formation of Cl mainly arises from the secondary photodissociation process CH{sub 2}Cl+h{nu}{yields}CH{sub 2}+Cl.
- OSTI ID:
- 20783215
- Journal Information:
- Journal of Chemical Physics, Vol. 124, Issue 3; Other Information: DOI: 10.1063/1.2158999; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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