Pranav Rane

Introduction

Recently, scientists have identified hydrogen-bearing species residing within vesicles in a lunar sample\(^1\) (Figure 1). These vesicles have been shown to form approximately 50 nanometers beneath the surface of the lunar regolith. However, the presence of \(\text{H}_{2}\text{O}\) within these vesicles has yet to be confirmed, and the physical processes governing vesicle formation are not entirely understood.

In this study, we present an initial characterization of lunar sample 75035.232 using photoluminescence (PL) and energy-dispersive X-ray spectroscopy (EDS). The results highlight the heterogeneity and complexity of the sample, which will serve as a baseline prior to any destructive experimentation.

Results and Discussion

The photoluminescence of samples provides information about the electronic excitation of the material. It works by emitting light from from four different colored dyes: red, orange green, and blue. The wavelength spectrum of these four dyes are illustrated in Figure 2.

This emitted light interacts with the material and can excite optically active regions in the sample. After excitation of certain regions, the sample can emit light of characteristic frequencies as it returns back to its ground state. Photoluminescence across all four dyes are taken on the top and bottom sides of the lunar sample in Figure 3 and Figure 4, respectively.

Additionally, we want to know the elemental composition of the sample. In other words, we want to know what atoms comprise it, what is the distribution of atoms, and where different atoms are in the sample. To do this, we use EDS which is shown in Figure 5.

We plan to use a couple other techniques such as focused ion beam (FIB) to liftout small portions of the sample to analyze with scanning transmission electron micrscopy (STEM). This will give us additional data that helps characterize the subsurface of the sample.