X-ray study of high-density amorphous water

X-ray diffraction measurements were performed at atmospheric pressure on a high-density form of amorphous ice obtained by pressurizing crystalline ice Ih at 77 K, up to 2 GPa. The low--momentum-transfer region of the determined structure factor is quite different from that corresponding to the low-density form of amorphous ice. However, the nearest-neighbor distance and coordination number are almost unchanged. The high density of this form of amorphous ice is explained by the strong distortion of the 0-0-0 angles from the ideal tetrahedral value.