W. M. Jackson, D. D. Xu, J. Huang

Chemistry Department, University of California, Davis, One Shields Ave, Davis, CA 95616

CS₂ has been identified as one of the parent molecules in comets and its absorption spectrum has been measured in laboratory under jet-cooled conditions. Coupled with the solar flux from 125 nm to 350 nm the solar absorption rate constants can be deduced as a function of wavelength, which shows that the rate constants from 192 nm to 209 nm are more than one order of magnitude higher than in other regions. There are two accessible channels in this region producing CS + S(³P) and CS + S(¹D). We report the experimental results on the energy distribution and branching ratio as a function of wavelength by means of ion velocity imaging technique. Product-selectivity is achieved by using a vacuum ultraviolet laser at different wavelengths to state-selectively ionize the products.

Acknowledgments: We gratefully acknowledge the support under a NSF grant CHE-9713929 and a NASA Planetary Atmospheres grant NAG5471.