Development of in-situ Depth Profiling for Extraterrestrial Materials with Isotope Nanoscope

Abstract

Lunar and asteroidal regolith contains noble gases derived from solar wind implantation. These particles preserve ancient solar wind, which can be revealed an energy distribution of the solar wind at the period of implantation. The energy distribution of ancient solar wind can be evaluated by depth profiling of noble gases into an extraterrestrial sample. Because typical solar wind ions are implanted at less than 50 nm from the sample surface, the particle surface for analysis must be kept in its original shape. In this study, particle samples were embedded in indium metal to adjust angle and position of the sample surfaces. We measured depth profiles for ¹⁶O⁺, ⁵⁶Fe²⁺, ⁴⁸Ti²⁺ and ²⁴Mg⁺ of ilmenite particles and a polished ilmenite. We obtained depth profiles of constant ion intensities from the ilmenite particles as well as the polished ilmenite. Reproducibilities for ion intensities normalized to ¹⁶O⁺ were up to 33% for particle samples and 19% for polished one.