Probing dynamic crystal growth of compressed hydrogen using dynamic-DAC, time-resolved spectroscopy and highspeed micro-photography

[摘要] Solidification and crystal growth processes of hydrogen (H2) have been studied under dynamic compression using dynamic-DAC (dDAC) in conjunction with time resolved Raman spectroscopy and high-speed microphotography. Liquid H2 was compressed at a compression rate of 43 GPa/s across the liquid/solid phase boundary, causing a discontinuous vibron shift at the onset of solidification. The real time sample images, on the other hand, showed that H2 solidifies into a characteristic, grain boundary free crystal, formed initially from the outside (or the edge of liquid) then grew into the central area within 11 ms. Interestingly, the time scale associated with the glassy solid formation is in good agreement with that of the discontinuous Raman frequency shift. The rate of crystal growth was measured to be 0.3 cm/s.

[发布机构] Department of Chemistry, Institute for Shock Physics, Washington State University, Pullman; WA; 99164, United States^1

[关键词] Compressed hydrogens;Compression rates;Crystal growth process;Dynamic compression;Glassy solids;Raman frequency shifts;Time-resolved Raman spectroscopies;Time-resolved spectroscopy