Test of solvent film for X-ray diffraction microscopy. (a) Test solution, 10%(v/v) glycerol/water in a cryoloop, high-pressure cryocooled at 200 MPa using the capillary-shielding method. The film, which is about 10 µm thick, looks transparent. The scale bar indicates 100 µm. (b) X-ray scattering (in the wide-angle regime) from the sample at 100 K, confirming that the water film was vitrified. The central peak position (3.3 Å) of the primary diffuse scattering indicates that HDA ice is present. (c) SAXS profiles from a 1 mm-thick high-pressure cryocooled sample of 15%(v/v) glycerol/water solution. Solid line, at 90 K. Dashed line, after warming to 200 K. The uniform and flat profile indicates that the high-density amorphous ice induced by high-pressure cryocooling is homogeneous in the given q range (0.035–0.35 Å−1). At 200 K, the HDA ice has transformed to hexagonal ice, with a dramatically increased non-uniform profile, indicating increased local density fluctuations in the 1.8–18 nm range. SAXS profiles have been scaled to match the high-q regions.