Unimolecular decomposition in the picosecond time-frame following field ionization of acyclic C4H8 alkenes

The kinetics of decomposition of 2H- and 13C-labelled but-1-ene and 2-methylpropene and 2H-labelled cis-but-2-ene following field ionization have been determined in the picosecond time-frame. Mechanisms are proposed to account for the major decomposition processes. Carbon randomization in the [but-1-ene]+˙ ion is a relatively slow process, and it is suggested that this fact could be due to slow vibrational relaxation.