Energy-dependent fragmentation of polystyrene molecule using size-selected Ar gas cluster ion beam projectile

A size-selected Ar gas cluster ion beam (GCIB) was applied to the SIMS of a polystyrene thin film. The size of Ar cluster ions are selected between 5000 to 500 atoms at an acceleration voltage of 5 and 10 kV using time-of-flight technique. Under this condition, the kinetic energy per constituent atom (E-atom) of the GCIB projectile was estimated to be 1 similar to 20 eV. The E-atom dependence of secondary ion yield of fragment species of polystyrene can be essentially classified into three types which are attributable to the relationship between the E-atom and the dissociation energy of the specified bonding site of the molecule. These results indicate that the site-specific bond breaking of molecules could be possible by adjusting the E-atom of size-selected GCIB. Copyright (C) 2010 John Wiley & Sons, Ltd.