The cubic and other structural forms of ice at low temperature and pressure

Abstract Deposits have been prepared by injecting water vapour on to a base at low temperatures in an electron-diffraction camera. Three types of diffraction patterns are found, depending on the temperature of the base. Below —140°C diffuse rings are obtained, between —140 and —120°C a sharp ring pattern characteristic of the diamond-type cubic pattern, and above —100°C the normal hexagonal pattern of ice also in the form of sharp rings. Deposits were also formed from the residual vapour in the camera, the method originally used by König. It is found that these deposits evaporate at a much higher temperature than those produced by injection, which suggests that these deposits are associated with some form of contamination. Experiments were also carried out with heavy water. The results are almost identical with those for ordinary water. The same three structural forms are produced under similar conditions, at temperatures which are slightly higher than those for ordinary water.