Carbon-cluster formation from polymers caused by MeV-ion impacts and keV-cluster-ion impacts

It has been observed that under MeV-ion bombardment of a polymer, such as polycarbonate (PC) or polyvinylidene fluoride (PVDF), large quantities of carbon clusters [Formula Presented] and [Formula Presented] are generated. However, when PC or PVDF is bombarded with keV atomic ions, very few carbon-cluster ions are produced. This different behavior was attributed to the different sputtering/desorption mechanisms for keV- and MeV-ion impacts. Low-energy keV ions deposit their energy into a solid through nuclear stopping, while MeV ions deposit their energy mainly through electronic stopping. The formation of carbon clusters is thought to be facilitated by the high-temperatures and high-energy densities produced in the region nearest the point of MeV-ion impact, the infratrack region. We have observed extensive carbon-cluster formation from PC and PVDF under keV-cluster-ion bombardment. Despite the vastly different velocities of the high- and low-energy projectiles, identical carbon-cluster trends are produced from MeV [Formula Presented] fission fragments and [Formula Presented] projectile impacts on the same target. This leads us to the conclusion that a polyatomic ion impact, which deposits its kinetic energy near the surface, may create a region of high-temperature and high-energy density that is similar to the infratrack of a MeV-ion impact.