Photodecomposition of Gaseous Bromoethane at 163.4 nm

Article abstract of DOI:10.1021/j100400a016

The 163.4-nm photolysis of gaseous C2H5Br has been investigated at 298 K over the pressure range 2-100 torr, using a bromine lamp.The effects of additives, N2,CF4, and NO, were also studied.In the pure system the observed reaction products and their respective quantum yields are C2H4 (ca.0.36), C2H6 (0.42-0.79), C2H3Br(0.1-0.24), CH3CHBr2 (0.24-0.32) and n-C4H10 (<0.01), most yields increasing with substrate pressure.An opposite trend is observed with increasing pressure of inert gases.The addition of NO as a radical scavenger completely supresses the formation of C2H6, C2H3Br, CH3CHBr2, and n-C4H10, and partially reduces the yield of C2H4.The results are interpreted in terms of the initial formation of two electronically excited states which are linked by way of a pressure dependence, one of which yields C2H4 by molecular elimination of HBr, while the second decomposes by carbon-halogen bond fission.The kinetics of the secondary process are discussed in some detail.