Ne- and O-filled ice XVII: a neutron diffraction study

• Published in: Physical chemistry chemical physics : PCCP 2019-07, Vol.21 (27), p.14671-14677
• Main Authors: Catti, Michele, del Rosso, Leonardo, Ulivi, Lorenzo, Celli, Milva, Grazzi, Francesco, Hansen, Thomas C
• Format: Article
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c9cp02218j

Deuterated ice XVII, a metastable solid water polymorph, was filled with Ne and O 2 at p 100 kPa and studied by in situ neutron diffraction (ILL, France). Powder patterns were collected in the ranges of 20-50 K (Ne) and 4.6-90 K (O 2 ). Rietveld refinement and difference Fourier techniques showed that the gas molecules were located inside the hexagonal channels of the host ice. Both Ne atoms and O 2 molecules are arranged in a spiral-like configuration off the channel axis, preserving the P 6 1 22 symmetry of the host in the case of Ne, but reducing it to P 6 1 in O 2 . A larger Ne absorption compared to Ne-filled ice II is observed, which is consistent with longer host-guest contacts producing smaller hydrophobic repulsion. In O 2 -filled ice XVII, instead, short O-D distances (2.37 Å) have attractive character and stabilize the structure. Ne and O 2 molecules are hosted by ice XVII in disordered spiral-like arrangements within the hexagonal channels.