Formation of the B3Π(0+) states of BrF and IF by atom recombination in the presence of singlet (1Δg, 1Σ +g) oxygen

Abstract

Combination of F ²P with Br ²P or I ²P ground state atoms in the presence of singlet O₂¹Δ_g, ¹Σ⁺_g, leads to formation of BrF B³Π(0⁺) or IF B³Π(0⁺), which were detected by observation of their band emission spectra (975 λ 483 nm), B³Π(0⁺)→X¹Σ⁺. It was shown that formation of BrF B³Π(0⁺) explicitly requires energy transfer from O₂¹Δ_g or ¹Σ⁺_g. The most probable excitation process is envisaged to occur by combination of Br ²P+ F ²P atoms (in the presence of a third body) to give BrF A³Π(1)(or possibly ³Π(2, 0^–)), followed by collisional energy transfer from singlet oxygen with BrF A³Π(1) to BrF B³Π(0⁺).

At least 38 new bands of the B→X system of BrF have been identified, and the previously uncertain vibrational numbering of the B³Π(0⁺) state has been confirmed. Vibrational constants are reported for the first time for levels of the X¹Σ⁺ ground state up to v″= 10, corresponding to an energy of 6262 cm^–1 above v″= 0. The available data on the dissociation energy of BrF are briefly surveyed, and a value of D°(BrF)= 2.384 eV is favoured.

For the B→X system of IF, many new bands have been observed, and vibrational constants for levels up to v″= 19 (10 381 cm^–1 above v″= 0) of the ground state are reported.