Nascent product population distribution in the reaction 16O(1D2)+H218O→16OH+18OH

Abstract

Nascent rotational and vibrational population distributions for the reaction ¹⁶O(¹D₂)+H₂¹⁸O→¹⁶OH+¹⁸OH have been determined using laser induced fluorescence detection of both OH species. Distributions were corrected for quenching by H₂O. The rotational distribution for ν‘=0 of ¹⁶OH is significantly hotter (19 500 K) than that obtained previously (2600 and 4600 K). In addition, rotational population in ν‘=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 Π(A’)Λ sublevels, with ν‘=0 and 1 having Λ population ratios of 1.5 and 1.2, respectively. The current data are better explained by an HOOH collision complex formed by insertion of ¹⁶O(¹D₂) into the H₂¹⁸O molecule. The complex probably has a relatively short lifetime, however, because the ¹⁶OH fragment is more rotationally and vibrationally excited than the ¹⁸OH fragment.