Electron Diffraction Study of Ice

抄録

Temperature ranges of formation of low temperature forms of ice and the hydrogen position in cubic and hexagonal forms were studied by electron diffraction. The ranges were found to vary according to the rate of condensation of water vapor and the discrepancies between the previous data for the ranges were attributed to the difference of the rate. Intensity of Debye-Scherrer patterns showed best agreement with Pauling’s half-hydrogen model for cubic ice as well as for hexagonal ice. Difference radial distribution and two-dimensional difference Fourier analysis of cubic ice revealed also that Pauling’s model is appropriate. From two-dimensional difference Fourier map of three different projections, O–H distance was found to be 0.96±0.03 Å. By calculation, it was shown that a shift of electron cloud causes no appreciable shift of potential peak. An elliptical elongation of hydrogen peak perpendicular to O–H bond was observed, which can be attributed to a shift of H–O–H angle from the tetragonal angle as well as to anisotropic thermal vibration.