Collisional energy transfer in predissociative OH laser-induced fluorescence in flames

Abstract

Collisional vibrational energy transfer from the predissociative v′ = 3 level of the OH A ∑+ state was studied with laser-induced fluorescence. For CH4/O2, CH4/air, and H2 /O2 flames at pressures ranging from 14 to 760Torr, the v′= 3 level was excited, and transfer into the lower v′ = 0, 1, 2 levels was measured. Energy transfer occurred in all flames, as exemplified by the 760-Torr CH4 /air flame in which only 30% of the total ultraviolet fluorescence emitted came from the initially excited v′ = 3 level. For quantitative measurements, one must either correct for vibrational energy transfer or alter the detection strategy to collect only fluorescence emitted by v′ = 3