[P-PS06] Lunar Science and Exploration

[PPS06-P26] A feasibility study of Auger electron spectroscopy on the sunlit lunar surface

*Masahisa Kato¹, Yuki Harada¹, Toru Matsumoto², Shaosui Xu³, Andrew R Poppe³, Jasper S Halekas⁴, Yohei Miyake⁵, Hideyuki Usui⁵, Masaki N Nishino⁶ (1.Graduate School of Science, Kyoto University, 2.The Hakubi Center for Advanced Research, Kyoto University, 3.Space Sciences Laboratory, University of California, Berkeley, 4.Department of Physics and Astronomy, University of Iowa, 5.Graduate School of System Informatics, Kobe University, 6.Graduate School of Science, The University of Tokyo)

Auger Electron Spectroscopy (AES) is one of the methods to investigate the chemical composition of sample material at a few nm depths from the surface. Recently, it has been realized that the Auger electrons from the sunlit lunar surface are observed by the Electrostatic Analyzer (ESA) onboard the ARTEMIS spacecraft orbiting the Moon (Xu et al., 2021). To explore the feasibility of AES with electron measurements by lunar orbiters as first envisioned by Lin and Gopalan (1991), we developed a numerical model that calculates the energy spectra of photoelectrons and Auger electrons emitted from the dayside lunar surface. The predicted energy spectra are in good agreement with the observations by ARTEMIS. Based on this model, we investigate the relative contributions of oxygen (O) and iron (Fe) Auger electrons to the observed electron fluxes at relevant energy channels. We then discuss the possibility of AES at the Moon to infer the ~nm depth composition of the lunar surface material with the currently available ARTEMIS data and with possible future electron measurements.