COLLISIONAL ENERGY-TRANSFER IN PREDISSOCIATIVE OH LASER-INDUCED FLUORESCENCE IN FLAMES

Collisional vibrational energy transfer from the predissociative v' - 3 level of the OH A SIGMA+ state was studied with laser-induced fluore scence. For CH4/02, CH4/air, and H-2/02 flames at pressures ranging fr om 14 to 760 Torr, the v' = 3 level was excited, and transfer into the lower v' = 0, 1, 2 levels was measured. Energy transfer occurred in a ll flames, as exemplified by the 760-Torr CH4/air flame in which only 30% of the total ultraviolet fluorescence emitted came from the initia lly excited v' = 3 level. For quantitative measurements, one must eith er correct for vibrational energy transfer or alter the detection stra tegy to collect only fluorescence emitted by v' = 3.