Kinetic energy release and mean life time of metastable ions produced from C3H3N

Metastable ions C3HnN+ (n = 1, 2 or 3) and C2H2+ produced by electron impact on the neutral C3H3N (acrylonitrile) undergo metastable decay reactions resulting in the fragment ions C3HmN+ (m = 1, 2) or C2H2+. We have monitored these reactions in a double focusing mass spectrometer of reversed B-E geometry. To identify the fragment ions and determine their kinetic energy release distribution (KERD), the mass-analyzed ion kinetic energy (MIKE) scan technique was utilized. For the above mentioned ions we obtained average KER values ranging from 9 up to 23 meV. Moreover, the fractions of decaying ions were measured. We have found the existence of two states of the metastable C2H2+ ion, one with a short life time of about 0.27 μs and the other one which is most likely a completely stable ion state.