Collisional deactivation of Br(4 2P1/2) by hydrogen isotopes

Abstract

The quenching of electronically excited bromine atoms Br(4 ²P_1/2) upon collision with H₂, HD, and D₂ has been studied at 300 °K. The temporal profile of the Br(4 ²P_1/2) concentration was monitored by observation of the time‐resolved attenuation of bromine resonance radiation at 153.2 nm. The probabilities of deactivation by the hydrogen isotopes are presented and compared to theoretical treatments based either upon long‐range coupling via mulitpolar interactions or explicit treatment of the nonadiabatic crossing probabilities computed using semiempirical potential surfaces. These results are then examined with a view toward assessing the importance of near‐resonant electronic–vibrational energy transfer in such an elementary system.