DYNAMICS OF THE H-]D+HOD HYDROGEN-EXCHANGE REACTION(D2O)

The gas-phase reaction dynamics of H + D2O --> D + HOD were studied us ing the laser photolysis/vacuum-UV laser-induced fluorescence (LP/VUV- LIF) ''pump-and-probe'' technique. Translationally excited H atoms wit h an average center-of-mass energy of E(c.m.) = 2.2 eV in the H-D2O fr ame were generated by the laser photolysis of H2S at 193 nm. Nascent D atoms produced in the reaction of H with room temperature D2O molecul es were detected under single collision conditions by VUV-LIF at the L yman-alpha transition. An absolute reaction cross section of sigma(R)( 2.2 eV) = (0.36 +/- 0.15) Angstrom(2) was determined by means of a cal ibration method. In addition, from the D atom Doppler profiles the ave rage fraction of the available energy released as product translationa l energy was determined to be f(T)(D + HOD) = 0.58 +/- 0.09.