Experimental characterization of ultrafast phenomena of secondary-ion emission induced by nanoscale energy deposition processes of energetic C60 impacts

Energetic C60 ion impacts in the sub-MeV to MeV energy range, which can provide secondary ions (SIs) necessary for the identification of organic materials in high emission yields, are excellent ionization methods for highly sensitive SI mass spectrometry. Energetic C60 ion-impact-induced SI emission is an ultrafast phenomenon that occurs at the nanoscale around the impact point through complex processes triggered by energy deposition by impact; it is therefore difficult to observe in situ. Here, we experimentally characterized this phenomenon using information about the emission yields of various negative-SI (N-SI) species over a wide range of C60 impact energies. We found that the N-SI emission phenomena are influenced by variations in the volume and geometry of the regions, where SI and/or precursor particles are preferentially produced depending on the deposited energy density.