Simple Molecular Systems at Ultrahigh Pressures

Carnegie Institution Of Washington, Washington DC

Investigators

Abstract

Technical A series of experimental studies of simple molecular systems to pressures above 300 GPa (3 megabars) over a broad range of temperatures will be carried out in this project. The research takes advantage of numerous developments in diamond-anvil cell techniques, including advances in analytical methods that utilize synchrotron x-radiation, optical spectroscopy, and transport probes. Hydrogen-dominant simple molecular solids, alloys, and selected elements will be examined to search for metallization and superconductivity. The crystal structures and electronic structures of newly discovered high-pressure phases will be determined using synchrotron x-ray techniques. Newly discovered high-pressure radiation chemistry will be explored. By improving our understanding of fundamental interactions in condensed matter, the project will impact areas of the physical sciences as diverse as nanoscience to the interiors of giant planets. The proposed work will showcase the synergy between fundamental science and new technologies, including addressing future energy problems. The project will advance technology necessary for studying matter under more extreme conditions. The research will seek to enhance capabilities major national facilities, and will train post-doctoral fellows as well as high school students, undergraduates, graduate students, and visiting investigators. Non-technical This project will explore the nature of matter through experimental studies of simple molecular substances subjected to pressures to above 3 megabars (3 million times atmospheric pressure) over a broad range of temperatures from near absolute zero to many thousands of degrees. The project takes advantage of numerous recent developments in the ability both to subject materials to these extreme conditions and to probe samples under those conditions with synchrotron x-rays, lasers, and new magnetic and electrical methods. Hydrogen-rich molecules will be transformed into new kinds of metals and superconductors, and the nature of metallic hydrogen, a predicted entirely new state of matter with exotic properties, will be explored. The dramatic changes in crystal structure and chemical bonding expected for materials under extreme conditions will be determined using a variety of synchrotron x-ray methods. The results impact materials science, nanoscience, planetary science, and astrophysics. The work will lead to development of new energetic materials, novel superconductors, gas storage materials, and superhard materials. The research will enhance capabilities at major national facilities, and will train high school students, undergraduates, graduate students, postdoctoral associates, and senior scientists. Impacts on both science and society broadly are therefore expected.