ABSOLUTE RATE CONSTANTS AND REACTIVE CROSS-SECTIONS FOR THE REACTIONS OF O((1)D) WITH MOLECULAR-HYDROGEN AND DEUTERIUM

The dynamics of the reaction of O(1D) with molecular hydrogen and deuterium has been investigated using ''superthermal'' O(1D) atoms generated by laser photolysis of N2O at 193 nm. H/D atom products have been detected under single-collision conditions by vacuum ultraviolet laser-induced fluorescence at the Lyman-alpha transition. With a calibration method using HCl photolysis as a source of well-defined H atom concentrations, the following absolute rate constants k and absolute reactive cross sections sigma(R) have been determined: k = (2.7 +/- 0.6) X 10(-10) cm3 s-1 molecule-1 and sigma(R)(0.12 eV) = 7.6 +/- 1.5 angstrom2 for the reaction O(1D)+H-2-->OH+H, and k = (2.3 +/- 0.5) x 10(-10) cm3 s-1 molecule-1 and sigma(R)(0.18 eV) = 7.0 +/- 1.4 angstrom2 for the reaction O(1D)+D2-->OD+D.