Amorphous Solid Water: An X-ray Diffraction Study

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Science  06 Dec 1974:
Vol. 186, Issue 4167, pp. 927-928
DOI: 10.1126/science.186.4167.927


Water vapor that condenses on a metal surface at 10°K forms a noncrystalline phase of estimated density 1.2 grams per cubic centimeter. X-ray diffraction data of high precision and resolution have been analyzed to yield oxygen atom pair correlation functions. The positional correlation in amorphous solid water extends over only a few molecular radii, and the radial distribution of nearneighbor oxygen atoms in amorphous solid water is qualitatively different from that found in the low-pressure ice modifications. Amorphous solid water is a useful material for liquid water models because it can be studied under conditions such that the effects of static disorder and thermal excitation can be separated.