Crossed Molecular Beam Study of F+C2H4, C2D4

Abstract

Crossed molecular beam experiments on $\mathrm{F}+{\mathrm{C}}_2{\mathrm{H}}_4$ , C₂D₄ have been performed with a mass spectrometric universal detector. Angular distributions of both substitution and abstraction reaction products were measured. The substitution reaction to form C₂H₃F (C₂D₃F) appears to proceed via a long‐lived complex, yet the recoil energy of the products has a broad distribution peaking at about half of the energy available. Experimental results for the substitution reaction are compared with the predictions of the RRKM theory of unimolecular decomposition. The discrepencies between them and inadequacies of the theory are discussed. Highly vibrationally excited DF was produced through the abstraction reaction of $\mathrm{F}+{\mathrm{C}}_2{\mathrm{D}}_4$ . DF formed in the forward direction of F motion is primarily in $\text{v′=4}$ . The formation of $\mathrm{DF}\text{(v′=4)}$ also suggests, from the conservation of total energy, that the internal excitation of the other reaction product C₂D₃ should be very small.