Dynamics of the H + D2O → D + HOD hydrogen exchange reaction

The gas-phase reaction dynamics of H + D2O → D + HOD were studied using the laser photolysis/vacuum-UV laser-induced fluorescence (LP/VUV-LIF) “pump-and-probe” technique. Translationally excited H atoms with an average center-of-mass energy of Ec.m. = 2.2 eV in the HD2O frame were generated by the laser photolysis of H2S at 193 nm. Nascent D atoms produced in the reaction of H with room temperature D2O molecules were detected under single collision conditions by VUV-LIF at the Lyman-α transition. An absolute reaction crosssection of σR(2.2 eV) = (0.36 ± 0.15) Å2 was determined by means of a calibration method. In addition, from the D atom Doppler profiles the average fraction of the available energy released as product translational energy was determined to be fT(D + HOD) = 0.58 ± 0.09.