The present high-resolution inelastic neutron scattering experiment on ice XVII, containing molecular hydrogen with different ortho/para ratio, allows to assign the H2 motion spectral bands to rotational and center-of-mass translational transitions of either {\it para}- or {\it ortho}-H2. Due to its structure, ice XVII confines H2 molecules to move in spiral channels of molecular size. Reported data demonstrate that H2 molecules rotate almost freely in these nanometric channels, though showing larger perturbation than in clathrate hydrates, and perform a translational motion exhibiting two low frequency excitations. The good agreement between experimental spectra and corresponding molecular dynamics results clearly enables to portray a picture of the confined motions of a hydrophobic guest within a metastable ice framework, i.e. ice XVII.
@article{arxiv.1706.09350,
title = {Dynamics of hydrogen guests in ice XVII nanopores},
author = {Leonardo del Rosso and Milva Celli and Daniele Colognesi and Svemir Rudic and Niall J. English and Christian J. Burnham and Lorenzo Ulivi},
journal= {arXiv preprint arXiv:1706.09350},
year = {2017}
}