Optical Properties of Fluid Hydrogen at the Transition to a Conducting State

R Stewart McWilliams; D Allen Dalton; Mohammad F Mahmood; Alexander F Goncharov

doi:10.1103/PhysRevLett.116.255501

Optical Properties of Fluid Hydrogen at the Transition to a Conducting State

Phys Rev Lett. 2016 Jun 24;116(25):255501. doi: 10.1103/PhysRevLett.116.255501. Epub 2016 Jun 22.

Authors

R Stewart McWilliams^{1

2

3}, D Allen Dalton¹, Mohammad F Mahmood^{1

3}, Alexander F Goncharov^{1

4

5}

Affiliations

¹ Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington D.C. 20015, USA.
² School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Peter Guthrie Tait Road, Edinburgh, United Kingdom EH9 3FD.
³ Department of Mathematics, Howard University, 2400 Sixth Street NW, Washington D.C. 20059, USA.
⁴ Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, 350 Shushanghu Road, Hefei, Anhui 230031, China.
⁵ University of Science and Technology of China, Hefei, Anhui 230026, China.

PMID: 27391733
DOI: 10.1103/PhysRevLett.116.255501

Abstract

We use fast transient transmission and emission spectroscopies in the pulse laser heated diamond anvil cell to probe the energy-dependent optical properties of hydrogen at pressures of 10-150 GPa and temperatures up to 6000 K. Hydrogen is absorptive at visible to near-infrared wavelengths above a threshold temperature that decreases from 3000 K at 18 GPa to 1700 K at 110 GPa. Transmission spectra at 2400 K and 141 GPa indicate that the absorptive hydrogen is semiconducting or semimetallic in character, definitively ruling out a first-order insulator-metal transition in the studied pressure range.