Electronic excitation of bromine to the B3Π(0 +u) state in the recombination of ground state Br2P atoms

Abstract

Emission has been observed from v′⩽ 9 of the B³Π(0⁺_u) state of Br₂ formed in the recombination of two ground-state Br(²P) atoms at 298 K and near 1 Torr total pressure of argon. Measurements of relative band intensities of the Br₂(B→X) system have been combined with Franck-Condon factors to show that the vibrational population distribution is thermal for 298 K in the range 5 ⩽v′⩽ 9, but that the lower levels 0 ⩽v′⩽ 4 are populated to only a small extent under these conditions. The results suggest that recombination of two Br(²P) atoms into the B³II(0⁺_u) state occurs in the vicinity of v′= 5 via a potential energy barrier of approximately 600 cm^–1.