"Professor Lee Yongjae’s Research Team Shows Missing Xenon might be trapped inside the earth"
The research team of Prof. Lee Yongjae (Earth System Sciences) recently discovered that xenon can be trapped inside a mineral’s structure under Earth’s crustal pressure and temperature conditions. “Irreversible xenon insertion into a small-pore zeolite at moderate pressures and temperatures” was published on July 20, 2014, in the online version of nature Chemistry. Xenon is an extremely rare and expensive noble gas. It is because the atmospheric xenon content of the Earth is less than 0.1 ppm. It is only the Earth and Mars in the solar system that has such depleted xenon content in its atmosphere. This has been called the “Missing Xenon” problem, and scientists have been trying to find where those missing xenon might be inside the Earth. Prevailing hypothesis has been that as xenon is heavy it could be trapped in the Earth’s core or in the mantle during the planet’s formation. The research team of Prof. Lee has suggested a new possibility that a large quantity of xenon can be trapped inside a zeolite mineral under moderate pressure and temperature conditions such as those found in the Earth’s crust. This new solution can now be applied to Mars, which is about half the size of the Earth and does not exert enough pressure and temperature conditions to trap xenon in its mantle and core. “More interesting is the chemical change that xenon exerts on the host zeolite mineral upon trapping,” said Prof. Lee. “Xenon pushes away half of its surrounding cations and change charges of the remaining half, turning the zeolite to have an unusual oxidation state for further chemical reactions.” The research team has used a miniature pressure device called diamond-anvil cell and synchrotron light at Pohang (PAL), Chicago (APS), and Stanford (SSRL). The first author of this paper, Seoung Donghoon, is a Ph.D student of Prof. Lee and is scheduled to work at Stanford, which is one of the partner institutions of the Global Research Laboratory program led by Prof. Lee. The mission of Prof. Lee’s research team is to use pressure to understand the Earth and to uncover hidden properties in materials. “Pressure is a clean, powerful, yet underexplored thermodynamic variable,” added Prof. Lee. “When pressure is applied, things have to change as we work harder under pressure.”