An optimised Quartz Crystal Microbalance setup to investigate the sputtering behaviour of bulk targets

Abstract

In modelling the exosphere formation of atmosphere-less planetary objects [1], the sputtering contributions is often calculated using Monte-Carlo style simulations like SRIM [2]. However, input parameters of these codes often need to be adapted to successfully describe experimental data [3]. To provide such experimental data, we perform sputter measurements in which we irradiate mineral samples relevant for modelling the surfaces of Mercury or the Moon. Usually, such experiments are performed using thin sample films deposited onto a Quartz Crystal Microbalance (QCM), allowing to determine mass changes in real time and in situ [4, 5]. Advancing on this technique, we conduct measurements using a previously presented setup with a second QCM facing the irradiated samples [6]. It collects particles liberated by sputtering and probes their angular distribution. This setup allows for experiments with bulk samples, including pellets made of mineral powders [7]. These are currently being used in addition to the aforementioned thin films on primary QCMs. The goal with these samples is to detect possible differences in sputtering behaviour between the amorphous films and the bulk specimens that might be explained by crystallinity [8].