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Updated: Mar 18, 2026

The Preparation of Electrohydrodynamic Bridges from Polar Dielectric Liquids
Published on: September 30, 2014
Optical Properties of Fluid Hydrogen at the Transition to a Conducting State
R Stewart McWilliams1,2,3, D Allen Dalton1, Mohammad F Mahmood1,3
1Geophysical Laboratory, Carnegie Institution of Washington, 5251 Broad Branch Road NW, Washington D.C. 20015, USA.
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.
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