Direct crystallographic study of phase V of solid hydrogen by single crystal X-ray diffraction

Measuring crystal structures of hydrogen at ultrahigh pressures is important for understanding the physics of this fundamental quantum solid and its pressure-induced phase transitions, especially metallization. There are multiple phase transitions on the pathway of hydrogen towards its metallization. Direct crystallographic studies of high pressure phases, especially those above multi-megabar pressures, requires state-of-art synchrotron technologies. We recently successfully measured single crystal X-ray diffraction data of phase IV of hydrogen above 200 GPa at multiple nano-probe beamlines. It is a great opportunity to take advantage of the nano-probe at ID27 with the updated 4th generation synchrotron to explore crystal structure of H2 at higher pressures. We target phase V above 325 GPa to verify theoretical models for this phase. Meanwhile, we would get hints on the feasibility of applying such technology for studying hydrogen, eventually metallic hydrogen, at even higher pressure.