| At a pressure in the vicinity of 150 to 250 GPa (100 GPa = 1 Mbar), molecular hydrogen is predicted to undergo an insulator-to-metal phase transition by band overlap. Developments in diamond-anvil-cell devices have pushed the pressure attainable in hydrogen into the range where observation of the insulator-to-metal transition in a static laboratory environment is possible. The search for this transition was the driving force behind the research reported in this thesis. In pursuit of this goal, we developed a better understanding of ruby fluorescence at high pressure, which is crucial to high-pressure experiments since the pressure shift of the ruby-fluorescence frequency is the standard very high pressure calibration scale. We have observed the insulator-to-metal transition in xenon at 132(5) GPa. Like hydrogen, xenon metallizes by closure of an indirect band gap above 100 GPa. Although there is tantalizing indirect evidence that hydrogen may metallize near 150 GPa, we pressurized hydrogen to 230 GPa and did not observe direct evidence of metallization. At this time, the insulator-to-metal transition pressure in hydrogen is still undetermined. |
