Br2 B 3Π (0u+) excitation spectra and radiative lifetimes in rare gas solids

Following excitation into either the bound B 3Π (0u+) vibrational levels or into the continuum, Br2 emits from the v=0 level of this state. Study of the excitation spectrum in the continuous region permits direct measurement of the B state contribution to the visible absorption and its separation from the stronger overlying 1Π1 continuum and confirms the assignment of the long wavelength shoulder on the visible absorption spectrum to the B state. A value of 7.3 μs is found for the B (0u+) v=0 emission lifetime in solid argon. Extrapolation based on the matrix data leads to an estimate of 12±2 μs for the radiative lifetime of the gas phase molecule.