SEM and ESR measurements on HOPG surfaces irradiated with Ar11+ and Ar1+

Abstract

Highly oriented pyrolytic graphite (HOPG) samples were irradiated with a highly charged ion (HCI) Ar11+ at a fluence of 1014 cm−2. After irradiation, scanning electron microscopy (SEM) was used to observe the irradiated trace. During SEM measurement, an electron acceleration voltage of 0.5, 1 and 5 kV was applied to measure the samples, respectively. The irradiated contrast can be observed in the Si surface at 0.5 kV, which could not be found at 1 kV or higher. The irradiated area becomes brighter than that of the unirradiated area. When Ar1+ was used to bombard the solid surface, the fluence should become of the order of 1015 cm−2. In this case, the irradiated contrast could be observed. It means HCI is able to enhance more effectively the surface modification. Furthermore, electron spin resonance was used to measure the surface of highly oriented pyrolytic graphite (HOPG). A clear resonant peak appears in the irradiated sample, which cannot be found in the pristine sample. The phenomenon could be related to defects induced by the HCI impact.