C60 ions of 1\u2009MeV are slow but elongate nanoparticles like swift heavy ions of hundreds MeV

H Amekura,K Yamada,K Narumi,A Chiba,S Yamamoto,Y Hirano,D Tsuya,Y Saitoh,N Okubo,N Ishikawa

doi:10.1038/s41598-019-49645-5

Abstract

This study reports that high fluence fullerene ion (C60+) irradiation of 1–6 MeV, which was made possible by a new-type of high-flux ion source, elongates metal nanoparticles (NPs) in amorphous SiO2 as efficiently as swift heavy ions (SHIs) of 200 MeV Xe14+, i.e., two orders of the magnitude higher energy ions. Comparing the irradiation effects induced by both the beams, the stopping processes of C60 ions in SiO2 are discussed in this paper. Despite of having almost the same elongation efficiency, the C60+ 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 SiO2 under 4 MeV C60 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 C60 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.

Highlights

which resulted in the enhancement of the excitation density[26]
While the NP elongation linearly increased with the fluence
It should be noted that the elongation is induced

Summary

Methods

Two types of NP samples were prepared: (i) Au NPs were formed in amorphous SiO2 by sequential vacuum depositions and annealing: At first, 3 nm thick of Au film was deposited on SiO2 substrate by electron beam vaporization. Rapid thermal annealing at 300 °C for 10 minutes transformed the continuous Au film to isolated NPs. the NPs were covered with SiO2 film of 100 nm thick by sputtering deposition. (ii) Zn NPs were formed by implantation of 60 keV Zn ions to SiO2 to a fluence of 1 × 1017 Zn+/cm[2]. Even without post thermal annealing, Zn NPs of 10.3 ± 2.3 nm in diameter were formed in the depth region between 20 and 70 nm

Results

Discussion

Conclusion