Absolute reactive cross section for the reaction H+D 2O→OD+HD: a comparison to the protonated case

Abstract

Using translationally hot H atoms generated via the photolysis of HBr at 193 nm, we have investigated the dynamics of the reaction H+D 2O→OD+HD at a center-of-mass energy of E c.m. = 2.53 eV. The nascent OD (ν=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 (ν=1) could be found. The absolute reactive cross section σ R=0.11±0.02 Å 2 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+H 2O→OH+H 2 at a comparable center of mass energy of E c.m.=2.52 eV.