NASCENT PRODUCT POPULATION-DISTRIBUTION IN THE REACTION O-16(1D2)+(H2O)-O-18-](OH)-O-16+(OH)-O-18

Nascent rotational and vibrational population distributions for the reaction O-16(1D2) + H-2 O-18 --> (OH)-O-16 + (OH)-O-18 have been determined using laser induced fluorescence detection of both OH species. Distributions were corrected for quenching by H2O. The rotational distribution for v" = 0 of (OH)-O-16 is significantly hotter (19 500 K) than that obtained previously (2600 and 4600 K). In addition, rotational population in v" = 0 of both OH species out to the thermochemical limit (9930 cm-1) cannot be explained by a model in which the OH rotational angular momenta of both fragments must be equal. Further evidence against that model is provided by the preferential population of PI(A') LAMBDA-sublevels, with v" = 0 and 1 having LAMBDA-population ratios of 1.5 and 1.2, respectively. The current data are better explained by an HOOH collision complex formed by insertion of O-16(1D2) into the H-2 O-18 molecule. The complex probably has a relatively short lifetime, however, because the (OH)-O-16 fragment is more rotationally and vibrationally excited than the (OH)-O-18 fragment.