Two- and three-body dissociations of C 3 H 6 isomer dications investigated by 4 keV/u Ar 8+ impact.

The fragmentation dynamics of two isomers of CH, cyclopropane and propene, induced by 4 keV/u Ar are investigated employing a reaction microscope. Four two-body and two three-body dissociation channels of CH dications are identified for each isomer, among which the channels involving CC bond breaking are found to be much more favored than H and H formation channels. The observation of the CH or H formation channels from cyclopropane are direct evidence of the proton migration within the carbon skeleton before dissociation. Obvious isomer effects are revealed by comparing the relative branching ratios of different channels of the two isomers. Moreover, it was shown that a sequential dissociation mechanism with H elimination prior to CC bond cleavage may be dominant for the two three-body dissociation channels for both isomers.