Abstract
New synchrotron infrared absorption and reflectivity techniques have been developed to test predicted band overlap metallization in and above 150 GPa at various temperatures. Measurements on both isotopes to maximum pressures of 216 GPa show no evidence for Drude excitations in the midinfrared to near-infrared spectrum. The most definitive are measurements on , which remains transparent down to 0.15 eV at 170 GPa and 83 K. The results put new bounds on the optical conductivity and possible band-gap closure at the 150-GPa transition. In addition to strong vibrational transitions, new infrared absorption features are observed.
- Received 7 November 1995
DOI:https://doi.org/10.1103/PhysRevLett.76.1667
©1996 American Physical Society