PRODUCT STATE-RESOLVED STUDY OF THE CL- COMPARISON OF THE DYNAMICS OFABSTRACTION OF PRIMARY VERSUS TERTIARY HYDROGENS((CH3)(3)CD REACTION )

The reaction of Cl atoms with the selectively deuterated isobutane, 2- methylpropane-2-d(1), has been investigated under single-collision con ditions using state-selective detection of the products by resonance-e nhanced multiphoton ionization (REMPI) in a time-of-flight mass spectr ometer. The reaction was initiated in a crossed, pulsed flow of the re agents by 355 nm photolysis of Cl-2 precursor. The internal state dist ributions of HCl and DCl products, formed by abstraction of primary an d tertiary hydrogen atoms, respectively, from the hydrocarbon reagent are reported. The degree of rotational excitation of both products was found to be very low. By comparison of the intensities of the HCl and DCl REMPI signals, the ratio of the yield of HCl to DCl product was f ound to be 3.3 +/- 0.4. With the known speed and angular distribution of the Cl reagent, it was possible to obtain information on the produc t center-of-mass angular distributions from measurement of the masses 37 and 38 time of arrival profiles. The DCl product is found to be mai nly backward scattered with respect to the incoming Cl atom, while the HCl product is sideways peaked. Inferences bn the dynamics of the two possible abstraction pathways from these results are discussed.