Isomerization Dynamics in the Symmetric and Asymmetric Fragmentation of Ethane Dications.

Hydrogen- or proton-migration-induced isomerization has recently been of concern for its critical role in the dissociation of organic molecules of astrophysical or biological relevance. Herein we present a combined experimental and theoretical study of the two-body C-C bond breakdown dissociation of ethane dication. For the asymmetric fragmentation channel CH + CH, the kinetic energy release measurements and quantum chemical calculations demonstrate that the reaction pathway involving hydrogen-migration-induced isomerization of [CH-CH] to [CH-CH] can be accessed the lowest triplet state rather than the ground singlet state of ethane dication. Interestingly, it is found that a considerable proportion of the yield of symmetric fragmentation CH + CH, which is usually considered from a direct Coulomb explosion and seemingly independent of isomerization, could come from the dissociation of ethane dication in the ground singlet state with the involvement of [CH-CH] isomerization to intermediate [HC(H)CH] of the diborane-like double-bridged structure.