Comparison of Secondary Ion Emissions from Carbon Nanotubes under Bombardments of MeV Si and Si₂ Clusters

The emission yields of H, H₂, H₃ and heavy ions from carbon nanotubes under bombardments of Si and Si₂ clusters in an energy range of 0.3-3 MeV per atom are measured by using the time-of-flight technique (TOF). The emission yields of the secondary ions increase with increasing energy of Si and the electronic stopping processes play an important role. The enhanced emission yields of secondary ions induced by Si₂ clusters at the low energies are clearly seen and attributed to the vicinage effect of the nuclear collision processes of cluster constituents and the secondary ion emissions are still dominated by electronic stopping processes at high energies.