Structure and morphology of gas phase deposited ice

Amorphous ice was prepared by deposition of H2O vapour diluted in heat exchange gases such as He or Ar at low temperatures (13 to 45 K). This technique is faster than the deposition of pure H2O vapour. The rapid sticking of condensing molecules on the cold solid leads to a poor short range order inside the grains. The high nucleation rate during vapour deposition results in small grain sizes and microporosity. Structure and morphology of the resulting amorphous ice samples were characterized by x‐ray diffraction. The radial distribution function was calculated from the diffraction data of pure ice and proved to be consistent with the Continuous Random Network model. Diffraction patterns of krypton layers on the amorphous ice reflect the morphology of the substrate: at the beginning micropores with a diameter of 15–20 Å and a volume of 0.045 cm3/g are filled. At higher mass coverages outer grain surfaces and large voids are covered by krypton.