Russell J. Hemley is the Director of EFree. His research explores the chemistry of materials over a broad range of thermodynamic conditions from low to very high pressures. He began his research career in molecular spectroscopy and electronic structure theory. An interest in the effects of high pressures on materials led him to the Geophysical Laboratory of the Carnegie Institution of Washington. There he began to apply and extend chemical physics techniques in high-pressure diamond anvil cell experiments. Since then, his research program has expanded to include high-pressure experimental and theoretical studies in condensed matter physics, earth and planetary science, and materials science. Some of his accomplishments include the discovery of new phenomena in dense hydrogen at megabar pressures; observations of unusual transformations in molecular materials and novel high-pressure molecular compounds; the creation of new superconductors, magnetic structures, glasses, and superhard materials under pressure. He is also involved in the continued development of high-pressure techniques, including optical methods, synchrotron radiation for diffraction and spectroscopy, and transport measurements.