ABSOLUTE REACTIVE CROSS-SECTION FOR THE REACTION H+D2O-]OD+HD - A COMPARISON TO THE PROTONATED CASE

Using transLationally hot H atoms generated via the photolysis of HBr at 193 nm, we have investigated the dynamics of the reaction H+D2O-->OD+HD at a center-of-mass energy of E(c.m.)=2.53 eV. The nascent OD (upsilon=0) rotational distribution was probed by laser-induced fluorescence. We found that only a small fraction (2.3%) of the total available energy appears as rotational energy of the OD product molecule and within our detection limit no OD (upsilon=1 ) could be found. The absolute reactive cross section sigma(R)=0.11+/-0.02 angstrom2 at E(c.m)=2.53 eV was determined by means of a calibration method and was found to be 2.4 times smaller than the reactive cross section of the reaction H+H2O-->OH+H-2 at a comparable center of mass energy of E(c.m.)=2.52 eV.