Evidence for a raised rim on pits in mica induced by keV/nucleon ions

Abstract

Nuclear tracks have been extensively studied and widely used in applications like archeological and geological dating, solar flare iostope determination, extraterrestrial material studies, super heavy elementary particle searches, etc. for more than three decades. Recently, scanning force microscopy (SFM) has proven to be useful for studying the pits induced by ions in the track recording energy range from several keV to several MeV per nucleaon on track recording material (e.g. mica) surfaces. SFM can provide topographical information on chemically etched orunetchedtrack pits at near atomic resolution in all three dimensions.We report here using a commercial SFM (NanoScope III, Digital Instruments, CA) in the study of a muscovite mica surfaces irradiated with 150keV Ar+ions. The mica was freshly cleaved before the irradiation. The SFM was operated with the amplitude resonance (tapping) mode to lower the interaction between a tip and specimen. We found pits on the mica surface after, but not before the irradiation, like those shown in Fig. la. Their number density was orders of magnitude less than the expected argon flux.