Crossed molecular beams study of O((sup 1)D) reactions with H(sub 2) molecules

摘要

Reaction dynamics of O((sup 1)D) atoms with H(sub 2) molecules was reinvestigated using the crossed molecular beams technique with pulsed beams. The O((sup 1)D) beam was generated by photodissociating O(sub 3) molecules at 248 nm. Time-of-flight spectra and the laboratory angular distribution of the OH products were measured. The derived OH product center-of-mass flux-velocity contour diagram shows more backward scattered intensity with respect to the O((sup 1)D) beam. In contrast to previous studies which show that the insertion mechanism is the dominant process, our results indicate that the contribution from the collinear approach of the O((sup 1)D) atom to the H(sub 2) molecule on the first excited state potential energy surface is significant and the energy barrier for the collinear approach is therefore minimal. Despite the increased time resolution in this experiment, no vibrational structure in the OH product time-of-flight spectra was resolved. This is in agreement with LIF studies, which have shown that the rotational distributions of the OH products in all vibrational states are broad and highly inverted.