Photodissociation of alkyl bromides

Abstract

The branching ratios for the production of Br(4 2P 1 2 ) following the broadband flash photolysis of the alkyl bromides, CH 3Br and C 2H 5Br, and the perfluorinated molecules, CF 3Br, C 2F 5 Br and n-C 3F 7 Br, have been determined using time-resolved atomic absorption spectroscopy. The production of electronically excited bromine atoms is shown to be inefficient in the case of the alkyl bromides while the perfluorinated molecules yield decreasing amounts of Br(4 2P 1 2 ) as the molecular complexity increases, i.e., CF 3Br > C 2F 5Br > C 3F 5Br > C 3F 7. It is also shown that the hydrogenated bromides deactive electronically excited atoms almost two orders of magnitude faster than do the perfluorinated bromides.