Dynamics of ethylene photodissociation from rovibrational and translational energy distributions of H2 products

Abstract

The dynamics of H2 elimination from ethylene was studied via a pump and probe technique utilizing an ultrahigh resolution vacuum ultraviolet laser system. H2 product internal and translational energy distributions were obtained for the photodissociation at 193 nm. The distribution of energy in H2 product from the dissociation of (1,1)-dideuteroethylene is also presented. Two separate H2 elimination channels are inferred: a 1,1 elimination producing the vinylidene radical and a 1,2 elimination producing the acetylene molecule. Differences between the vibrational, rotational, and translational energy distributions for these two channels are discussed and correlations between product internal and translational energy are presented. A comparison with ab initio calculations of the transition state configurations for these processes is made. We suggest that the H2 elimination process may be nonstatistical in nature. The D atom elimination from C2D4 was examined and kinetic energy distribution for this product measured.