ISOTOPIC-SUBSTITUTION EFFECTS ON ACETIC-ACID PHOTOFRAGMENTATION DYNAMICS

The internal and translational energy distributions of the OD X (2) Pi photofragment resulting from the 218 nm photolysis of acetic acid-d a re presented. Comparison of these results with those of acetic acid-h photolysis reveals the effects of isotopic substitution on the alpha-c leavage photodynamics of (1)(n, pi)-excited acetic acid. The OD produ ct contains only approximately 17% more rotational energy than the cor responding OH fragment, and the OD translational energy distributions broaden with increasing fragment rotational level. A pure impulsive mo del for the dissociation dynamics is inadequate to explain these resul ts. Interpretations which also include contributions from excited stat e bending motions may be more realistic.