Hydrogen and helium are believed to be the most abundant and simplest elements in the universe. The solar wind, composed predominantly of H and He, is consistently implanting volatiles onto planetary surfaces. Terrestrial sources of ³He are rare while the moon lacking atmosphere is a relatively easily accessible reservoir. However, the understanding of ³He is mostly based on limited lunar returned samples and remote sensing data, resulting in a far from accurate evaluation of nuclear resources.
Nominally anhydrous minerals (NAMs) composing Earth and planetary rocks incorporate microscopic amounts of hydrogen in their crystal structure (Keppler et al.,2006), playing a crucial role in the geodynamic evolution of the Earth and other planets. Albeit being abundant only in trace amounts, the presence of hydrogen is known to significantly alter the physical, rheological, and chemical properties of rock-forming mantle minerals (Schmandt et al., 2014) with large-scale impacts for lithospheric mantle stability (Peslier et al.,2010; Xia et al.,2019). However, the volatile evolution and distribution of NAMs are controversial.
Thus, confining hydrogen and ³He concentrations of NAMs in terrestrial and extra-terrestrial samples is a promising endeavor. Here, we present a novel approach to constrain trace element concentrations in NAMs using nano-scale Nuclear Magnetic Resonance (NMR) spectroscopy (Li et al.,2023; Meier et al.,2023). We are able to demonstrate that this technique is in excellent agreement with standard methods (e.g. NanoSIMS and FTIR) and surpasses their detection limits by several orders of magnitude. Our measurements show that a ³He mass sensitivity of about 87 wt-ppb in micro-meter-sized Chang’e-5 lunar samples can be detected. Given the unique advantages of non-destructiveness, stand-alone independence, and record trace element mass-sensitivity show that this novel NMR approach is promising for rare and precious samples of terrestrial or extraterrestrial origin.
 

PPb detection limit,Nano-scale NMR Spectroscopy,Nominally anhydrous mineral and material