15min:

H. MARK LAMBERT AND PAUL J. DAGDIGIAN, Department of Chemistry, The Johns Hopkins University, Baltimore, MD 21218.

Vibrationally excited CH₃Cl is prepared by laser excitation in the fourth overtone C-H stretch band near 725 nm and photodissociated at fixed wavelengths near 240 nm which also probe either the H, Cl(²P_3/2), or Cl(²P_1/2) photofragments via (2+1) resonance enhanced multiphoton ionization (REMPI) in a time-of-flight mass spectrometer. Jet cooling of the CH₃Cl reveals two partially resolved bands in the overtone excitation spectrum which are assigned to [5,0,0] and [4,0,0] + 2₂. The product yields from the photolysis of vibrationally excited CH₃Cl show decided enhancement compared to photolysis of the ground state. Branching ratios of atomic products are also determined for photolysis of both excited and ground state CH₃Cl. The ratio of Cl(²P_1/2) to Cl(²P_3/2) is dramatically larger for photolysis of vibrationally excited vs. ground state CH₃Cl.