Surface-induced dissociation of small carbon cluster negative ions (C-n(-), n=5-12): Correlation between the dissociation patterns and stability of fragment ion-neutral pairs

We report detailed study of surface-induced dissociation (SID) of small car bon cluster negative ions (C-n(-), n = 5-12) in collision with Si substrate s. Fragment mass spectra have been observed in the collision energy range o f 0-10 eV/atom. Neutral C-3 loss occurred at collision energies lower than 2 eV/atom. In the medium energy range (2-6 eV/atom), a marked even-odd diff erence in the dissociation has been observed: even fragment ions were predo minantly generated from incident odd clusters, whereas both even and odd fr agment ions from incident even clusters. These results are qualitatively in good agreement with the formation energies of fragment ion-neutral pairs c alculated using the experimentally determined binding energies of ions and neutrals. Ar elevated collision energies (6-10 eV/atom), further fragmentat ion and electron detachment from fragment ions occurred and smaller cluster ions with even n were preferentially generated.