Muonium in stishovite: implications for the possible existence of neutral atomic hydrogen in the earth's deep mantle.

Nobumasa Funamori,Norimasa Nishiyama,Tomoko Sato,Ryosuke Kadono,Teiichiro Matsuzaki,Akihiro Koda,Masanori Miyazaki,Tetsuo Irifune,Takashi Taniguchi,Daisuke Wakabayashi,Masatoshi Hiraishi,Kenji M Kojima,Dai Tomono

doi:10.1038/srep08437

Abstract

Hydrogen in the Earth's deep interior has been thought to exist as a hydroxyl group in high-pressure minerals. We present Muon Spin Rotation experiments on SiO2 stishovite, which is an archetypal high-pressure mineral. Positive muon (which can be considered as a light isotope of proton) implanted in stishovite was found to capture electron to form muonium (corresponding to neutral hydrogen). The hyperfine-coupling parameter and the relaxation rate of spin polarization of muonium in stishovite were measured to be very large, suggesting that muonium is squeezed in small and anisotropic interstitial voids without binding to silicon or oxygen. These results imply that hydrogen may also exist in the form of neutral atomic hydrogen in the deep mantle.

Highlights

Science, 22607 Hamburg, Germany, and Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Tokyo 102-0075, Japan
It seems possible that the hydrogen which is not directly related to lattice defects of silicates and has not so far been recognized sufficiently in earth science may exist in the mantle
We present the results of Muon Spin Rotation (mSR) spectroscopy to show the possible existence of neutral atomic hydrogen in small and anisotropic interstitial voids of stishovite

Summary

Introduction

22607 Hamburg, Germany, and Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Tokyo 102-0075, Japan. In the field of applied physics, hydrogen in perfect crystals of low-pressure phases of SiO2 has been studied by the methods to probe H more directly[6,7,8,9,10], such as Muon Spin Rotation (mSR) and Electron Paramagnetic Resonance (EPR), to obtain a better understanding of Metal-Oxide-Semiconductor (MOS) devices. In those studies, it has been reported that hydrogen can exist in interstitial voids of structure. MSR was conducted on powder and pellet samples to clarify intrinsic properties of stishovite (see Methods)

Methods

Results

Conclusion