Vibrationally mediated photodissociation of [C.sub.2][H.sub.4.sup.}

The vibrationally mediated photodissociation dynamics of [C.sub.2][H.sub.4.sup.} excited through the [B.sup.2][A.sub.g] state are described. Analysis of the multimass images yielded both the translational energy distributions for the two dissociation channels and the branching between them as a function of excitation energy and the dissociation of ions consistently gave enhanced branching to the H elimination channel.