LASER DOUBLE-RESONANCE MEASUREMENTS OF THE QUENCHING RATES OF BR(2P1/2) WITH H2O, D2O, HDO, AND O2

Quenching rate constants for spin-orbit excited Br* atoms (2P1/2) with H2O, D2O, HDO. and O2 are measured at 300 K using a two-laser pump-probe technique. The rate constants and +/- 1 sigma-error bars for the water species are: H2O, (5.1 +/- 0.3) x 10(-11) cm3 molecule-1 s-1; HDO, (1.9 +/- 0.4) x 10(-11) cm3 molecule-1 s-1; D2O, (2.2 +/- 0.4) x 10(-12) cm3 molecule-1 s-1. The relative rates for the water species are in qualitative agreement with models for electronic-to-vibrational energy transfer based upon dipole-quadrupole coupling. Quenching of Br* by oxygen is found to be extremely inefficient (1.5(-1.5)+0.4) x 10(-15) cm3 molecule-1 s-1. which is in disagreement with previously reported results by four orders of magnitude.