Extremely rotationally excited OH from water (HOD) photodissociation through conical intersection.

Photodissociation of HOD from the B state has been studied using the Rydberg "tagging" time-of-flight technique. Experimental results indicate that extreme rotational excitation in the OH(X,v = 0) product ( N up to 50 or so) is produced through the conical intersection dissociation pathway such that some of the OH product states lie above the O((3)P)+H dissociation limit, which are supported only through large centrifugal barriers. The population distribution for OH(X,v = 0) also shows an alternation with N, similar to that observed for H(2)O that is attributed to dynamical interference. The tunneling rates of these extremely rotationally excited OH molecules are also analyzed.