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

The dynamics of the reaction of O(1D) with molecular hydrogen and deut erium has been investigated using ''superthermal'' O(1D) atoms generat ed by laser photolysis of N2O at 193 nm. H/D atom products have been d etected 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 concen trations, the following absolute rate constants k and absolute reactiv e 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) cm 3 s-1 molecule-1 and sigma(R)(0.18 eV) = 7.0 +/- 1.4 angstrom2 for the reaction O(1D)+D2-->OD+D.