Laser-desorption ionization of graphite produced small carbon-cluster ions in a time-of-flight tandem mass spectrometer. Ions with C 9–11 + underwent keV collision-induced dissociation, and the resulting product ion distributions and the molecular processes leading to those products were computationally explored using density functional theory. All three ions undergo the previously observed loss of neutral C 3 , while C 9 + ions also exhibited loss of C 2 . A combination of density functional theory calculations and RRKM theory demonstrated that the reactions are preceded by the rapid interconversion of linear and cyclic forms. For C 9 + , dissociation by loss of C 1 , while lower in energy than C 2 , was disfavoured by a dissociating complex that tended to an excited state of C 8 + having quartet character. For all three ions, RRKM analysis of the dissociation from both isomers concluded that, irrespective of their relative energies, products were formed from both isomers, but the linear isomer dominates as size increases. • Laser-desorption ionization of graphene produced small carbon cluster cations. • CID of C 9 + , C 10 + and C 11 + leads to loss of C 2 and C 3 neutrals. • Isomerization of cyclic and linear isomers of each was explored with DFT and RRKM. • Dissociation products found to be formed largely from the linear isomer.
Fernando et al. (Sun,) studied this question.