Preferential Sputtering of DNA Molecules on a Graphite Surface by Ar Cluster Ion Beam

Abstract

The process of sputtering by bombardment with gas cluster ions was investigated from the perspective of the kinetic energy per constituent atom (E atom ) of an incident cluster ion, which determines the threshold for the formation of craterlike defects by irradiation of an argon gas cluster ion beam (Ar-GCIB) onto a graphite surface. Furthermore, DNA molecules adsorbed on a graphite surface were preferentially sputtered by adjusting E atom of the Ar-GCIB down to this threshold, while the substrate graphite surface retained its carbon lattice structure without the formation of craterlike defects. These results indicate that a GCIB could be used as a primary ion beam for secondary ion mass spectrometry (SIMS), which would enable the preferential analysis of an adsorbed layer on a substrate without causing damage to the substrate.