State-selected photodissociation of D₂O

The effect of selective vibrational preparation of the parent on its absorption cross section and on the vibrational distribution of the photofragments is studied in D₂O. Rovibrationally excited D₂O molecules are prepared in the | 03 〉^- state by infrared excitation and photolyzed via the A(¹B₁) state by 193 nm photons. The OD fragments are detected by laser-induced fluorescence. The ≈ 1 eV vibrational excitation of D₂O results in a five orders of magnitude increase in the absorption cross section and its subsequent photolysis yields OD with (v = 1)/(v = 0) = 0.39±0.07. The significant population of both vibrational states of OD may help in testing quantitative agreement between experiment and future theoretical studies of state-selected photodissociation.