CL (2PJ) FINE-STRUCTURE QUANTUM YIELDS FROM UV DISSOCIATION OF PCL3, CCL4, CHCL3 AND CL2 IN A SUPERSONIC JET

Jet-cooled phosphorus trichloride, carbon tetrachloride, chloroform an d molecular chlorine are photodissociated in the UV wavelength range 2 35-238 nm. Chlorine atom photofragments Cl (P-2(3/2)) and Cl (P-2(1/2 )) are detected via resonance-enhanced (2 + 1) ionization throughout t he 232-238 nm wavelength region. The relative Cl yields, phi* = [Cl*] /([Cl] + [Cl]), are measured for both Cl-35 and Cl-37 isotopes using the two-photon atomic transitions at 235.3 nm for Cl and 237.8 nm for Cl. Preliminary results indicate that the Cl* yields are different fo r the two isotopes for some of the precursors. In addition, we obtaine d the two-photon oscillator strength of the Cl transition at 237.7 nm relative to the Cl transition at 237.8 nm. The advantage of using the two-photon Cl transition at 237.7 nm for quantum yield measurements i s discussed.