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

Abstract Metastable ions C 3 H n N + ( n  = 1, 2 or 3) and C 2 H 2 + produced by electron impact on the neutral C 3 H 3 N (acrylonitrile) undergo metastable decay reactions resulting in the fragment ions C 3 H m N + ( m  = 1, 2) or C 2 H 2 + . 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 C 2 H 2 + 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.