A team of scientists led by Drs. Thomas Meier and Renbiao Tao from the Center for High Pressure Science and Advanced Technology Research (HPSTAR) has made significant breakthroughs in the development of detection methods of trace volatile elements within terrestrial and extraterrestrial samples, a development poised to enhance our understanding of planetary evolution. The research published in Nature Communications, introduces a cutting-edge approach using micro-scale Nuclear Magnetic Resonance (NMR) spectroscopy to analyze nominally anhydrous minerals (NAMs) from Earth and Planets.

Caption: Schematic representation of the detection method. a) Due to small sample sizes, detection of the NMR transient is accomplished by the use of magnetic flux-focusing Lenz lenses. b) Since signal intensities are directly proportional to the spin density of each spin system, this method provides a direct measurement of the spin density in a microscopic specimen. c) Moreover, abundant NMR-active nuclei in the same sample (e.g. aluminium) can be employed as internal reference standards, making this method fully stand-alone and non-destructive for trace-element quantification.

The volatiles on Earth and planets are not only essential materials for life but also key elements for maintaining Earth's habitability. Therefore, the quantitative analysis of volatiles in natural and synthetic geological samples is fundamental for studying the origin and evolution of Earth's and planetary volatiles. Yet, traditional methods (e.g., FTIR or SIMS) have struggled to detect these volatile elements with the necessary precision and detection limits. In a new research, the HPSTAR team has developed a method for non-destructive analysis of trace elements such as hydrogen, helium, fluorine, and phosphorus in geological samples at the micron scale. The new technique leverages the enhanced mass sensitivity of micro-scale NMR, offering a significant leap forward in detecting and quantifying these elusive trace volatile elements. By selecting aluminum, a major element in geological samples, as an internal standard, this method can accurately quantify the content of key volatiles in glasses and nominally anhydrous minerals. Additionally, it has improved the mass sensitivity of quantitative nuclear magnetic resonance spectroscopy to 40 ng/g (wt-parts per billion).

"Our method provides a level of sensitivity that allows us to detect volatile elements as minute as 40 ppb in a single mineral grain," explained the first author Dr. Yunhua Fu." This capability represents a substantial improvement over existing techniques, enabling us to explore the volatile content of minerals at an unprecedented scale."

"Micro-scale NMR spectroscopy represents a transformative tool for geoscientists, which allows us to explore the invisible — those minute trace elements that play a critical role in the formation and evolution of planets," emphasized Dr. Thomas Meier. "By improving our ability to detect and quantify these elements, we are opening new doors to understanding the processes that have shaped not just Earth, but other planetary bodies as well."

The implications of this research extend beyond the study of Earth’s mantle. The ability to measure trace volatiles with such precision opens new avenues for understanding the volatile histories of other planetary bodies, including the Moon, Mars, and various asteroids. This, in turn, can offer insights into the processes that governed the early solar system, including planetary formation, differentiation, and volcanic activity.

"By improving our understanding of the origin and distribution of volatiles within NAMs, we can better interpret the thermal and chemical evolution of Earth’s planetary interiors. This has promising implications for our models of planetary dynamics and evolution," added Dr. Renbiao Tao. "However, NMR also has its limitations. For example, it is challenging for NMR to analyze iron-bearing samples due to the strong magnetism of iron nuclei. The quantitative NMR analysis can provide excellent reference standards for SIMS analysis. We anticipate that by combining the advantages of NMR quantitative analysis with SIMS in-situ analysis, more constraints on the origin and evolution of Earth's and planetary volatiles will be provided in the future." 

The research is expected to have wide-reaching impacts in geoscience, providing a robust tool for future studies aimed at unraveling the complex volatile evolution history of Earth and other planetary systems. As the scientific community continues to explore the volatile content in geologically important systems, the method developed by the HPSTAR team stands to play a pivotal role.

近日，北京高压科学研究中心陶仁彪课题组和Thomas Meier 课题组合作，在名义上无水矿物中挥发份元素定量测试方面取得了阶段性进展。该研究开发了一种利用核磁共振无损分析微米尺度地质样品中氢、氦、氟、磷等微量元素的方法。该方法可以准确定量玻璃以及名义上无水矿物中关键挥发份元素的含量，可将定量核磁共振波谱的质量灵敏度提升至40 ng/g。该技术可用于平行定量分析地质样品中多种微量挥发性元素，为我们了解地球与行星挥发份的演化历史提供重要的技术支持。相关工作以 “Trace Element Detection in Anhydrous Minerals by Micro-scale Quantitative Nuclear Magnetic Resonance Spectroscopy ”为题发表于Nature Communications上。