Electronic quenching of highly rotationally excited OH(A 2Σ, ν′=0, 1) by H 2O

Abstract

Population of specific high-lying rotational levels of OH (A 2Π) in ν′=0 and 1 is achieved by tunable dye laser excitation of the A←X transition of the OH product formed in O( 1D)+H 2O→2 OH(ν′=0, 1). Observation with a fast transient recorder/signal averager of the spontaneous A→X emission temporal profile as a function of H 2O pressure yields the rate constant, k H 2O , for collisional quenching following excitation of specific OH(A 2Π, ν′, N′, F′) states. This rate decreased with increasing rotational excitation in sensible agreement with a model in which long-range attractive forces on a highly directional potential surface dominate collisional quenching. Extrapolation of the observed emission lifetimes to P H 2O =0 yields optical lifetimes in good agreement with previously reported values.