Zaghoo, MohamedSalamat, AshkanSilvera, Isaac2016-11-082016Zaghoo, Mohamed, Ashkan Salamat, and Isaac F. Silvera. 2016. “Evidence of a First-Order Phase Transition to Metallic Hydrogen.” Physical Review B 93 (15) (April 15). doi:10.1103/physrevb.93.155128.2469-9950http://nrs.harvard.edu/urn-3:HUL.InstRepos:29374821The insulator-metal transition in hydrogen is one of the most outstanding problems in condensed matter physics. The high-pressure metallic phase is now predicted to be liquid atomic from T=0 K to very high temperatures. We have conducted measurements of optical properties of hot dense hydrogen in the region of 1.1-1.7 Mbar and up to 2200 K. We observe a first-order phase transition accompanied by changes in transmittance and reflectance characteristic of a metal. The phase line of this transition has a negative slope in agreement with theories of the so-called plasma phase transition.en-USJournal Article2016-11-0810.1103/PhysRevB.93.155128