Research Highlights

Evidence for a new phase of dense hydrogen above 325 gigapascals

Almost 80 years ago it was predicted that, under sufficient compression, the H–H bond in molecular hydrogen (H2) would break, forming a new, atomic, metallic, solid state of hydrogen. Reaching this predicted state experimentally has been one of the principal goals in high-pressure research for the past 30 years. Using in-situ high-pressure Raman spectroscopy, a team headed by Prof. Eugene Gregoryanz studied hydrogen and its heavier isotopes hydrogen deuteride and deuterium at room temperature to pressures above 380 GPa. The experimental data indicate that above 325 GPa H2 and HD adopt a new solid phase, phase V. This phase may be a precursor to the non-molecular (atomic and metallic) state of hydrogen that was predicted 80 years ago.