Professor Reisler is supported by a grant from the Experimental Physical Chemistry Program for a two-part study: One is the photodissociation dynamics of small polyatomic molecules with emphasis on the influence of the electronic structure of the excited state on the dynamics. The other is collisional dissociation of highly vibrationally excited molecules. The experiments will be done with crossed molecular beams, multiphotoionization detection and photoinitiated vibrational excitation; product state distributions will be measured. The ultimate goal is to achieve better control over the outcomes of molecular dissociations by selective access to specific regions of the potential surface. The immediate goal is to study the evolution of parent molecule excitation into product fragment excitations. The systems to be studied are cyanogen halides and related molecules. %%% The influence of the stretching and bending motions in the molecule on the final outcome when light causes a molecule to come apart into fragments will be studied. The questions to be answered in this study are: What products are formed and how is the energy disposed of among these fragments, that is, what is the energy distribution into the various forms of internal energies of the fragments?