Proposed Molecular Beam Determination of Energy Partition in the Photo Dissociation of Polyatomic Molecules

Conventional photochemical experiments give no information about the partitioning of energy between translational recoil and internal excitation of the fragment molecules formed in photodissociation of a polyatomic molecule. In a molecular beam experiment, it becomes possible to determine the energy partition from the form of the laboratory angular distribution of one of the photodissociation products. A general kinematic analysis is worked out in detail, and the uncertainty introduced by the finite angular resolution of the apparatus and the velocity spread in the parent beam is examined. The experimental requirements are evaluated for the photolysis of methyl iodide by the 2537 0 Hg line. *Support received from the U. S. Atomic Energy Commission and the Alfred Po Sloan Foundation is gratefully acknowledged. tNational Science Foundation Predoctoral Fellow, 1961-64. *Present address: Department of Chemistry, Harvard University, Cambridge, Massachusetts, 02138.