LASER-INITIATED FREE-RADICAL CHLORINATION OF PROPANE IN AMORPHOUS THIN FILMS: TEMPERATURE DEPENDENCE FROM 15 TO 77 K

Article abstract of DOI:10.1021/j100321a025

The free-radical chlorination of propane, deposited as a thin amorphous film, has been investigated at temperatures ranging from 15 to 77 K.Reactions are initiated by pulsed laser photolysis of chlorine molecules at 308 nm.Product yields and branching ration are characterized by Fourier transform infrared absorption spectroscopy.The inherent reactivity of chlorine atoms toward secondary versus primary hydrogens (when corrected for the greater number of primary sites) decreases from 17:1 at 77 K to 2.3:1 at 60 K and below.Over the same temperature range the quantum yield is observed to increase from 0.12+/-0.02 to 0.70+/-0.06.These results reflect the onset of translationally excited (hot) chlorine atom reactions.