C ions of 1 MeV are slow but elongate nanoparticles like swift heavy ions of hundreds MeV.

This study reports that high fluence fullerene ion (C) irradiation of 1-6 MeV, which was made possible by a new-type of high-flux ion source, elongates metal nanoparticles (NPs) in amorphous SiO as efficiently as swift heavy ions (SHIs) of 200 MeV Xe, i.e., two orders of the magnitude higher energy ions. Comparing the irradiation effects induced by both the beams, the stopping processes of C ions in SiO are discussed in this paper. Despite of having almost the same elongation efficiency, the C irradiation induced ~10 times more efficient sputtering due to the clustering enhancement and/or the synergy effect. Ion tracks of ~10.4 nm in diameter and 60-80 nm in length were observed in crystalline SiO under 4 MeV C irradiation While the track diameter was comparable to those by SHIs of the same electronic stopping, much shorter track lengths than those predicted by a rigid C molecule model indicates that the fragmentation occurred due to nuclear collisions. The elongation of the metal NPs was induced only down to the depth where the tracks were observed but not beyond.