X-ray diffraction of metastable structures from supercooled liquid hydrogen

We report time resolved observations of the crystallization from liquid hydrogen, supercooled to temperatures below the melting point, using 11.2 keV X-ray diffraction from the Linac Coherent Light Source (LCLS). Changes to the metastable solid and liquid structure factors have been dynamically measured. This allows for a direct determination of the lowest energy crystal polymorphs, the stacking probabilities, as well as the liquid and solid densities and temperatures. Such measurements provide experimental evidence of an Arrhenius-like growth kinetics along the stacking direction during supercooling.. Authors: Fletcher, Luke B. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); SLAC]; Levitan, Abraham L. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)]; McBride, Emma E. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); European XFEL, Schenefeld (Germany)]; Kim, Jongjin B. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)]; Alves, Eduardo P. [SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Univ. of California, Los Angeles, CA (United States)]. DOE Contract: AC02-76SF00515; AC52-07NA27344. Subjects: 36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; hydrogen crystallization; stacking faults; supercool; x-ray diffraction