Collisional Dynamics of the Triplet-B

When Br_2 is combined with F atoms and discharged oxygen in a flow tube, BrF rm B^3Pi(O^+) is produced in a highly non-thermal distribution peaking at v ^' = 3. The emission was linearly dependent on the rm O_2(b^ 1Sigma) concentration. The observed dependence of the BrF(B) emission on Br_2 and atomic oxygen is inconsistent with a steady state prediction of a sequential excitation mechanism, where BrF(X) is excited by successive collisions with singlet oxygen. The experimental data are consistent with a three body mechanism involving Br and F atoms. Electronic quenching of BrF(B) by a number of collision partners (Br_2, CO _2, O_2, N _2, CF_4, SF _6, Ar) was examined for three vibrational levels using laser induced fluorescence (LIF) techniques. The rate coefficients ranged from <6 times 10^{-14} cm^3/(moleculescdot s) as an upper limit for argon, to (6.86 +/-.18) times 10 ^{-11} cm^3/(molecules cdots) for Br_2. Vibrational transfer in BrF(B), induced by the BrF production mix (CF_4, Br _2, F) was measured by observing the spectrally resolved LIF emission from each vibrational level after an initial excitation of BrF(B) v^' = 5. This vibrational transfer obeyed a simple theoretical prediction, the Montroll-Shuler model. A single fundamental rate coefficient k^{rm v}(1,0) = (3.5 +/-.6) times 10^{-12 } cm^3/(molecule cdots) characterizes vibrational transfer.