重水素化テトラヒドロフラン水和物クラスレートにおける水素の非弾性中性子散乱研究
Neutron inelastic scattering measurements were performed on hydrogen molecules adsorbed within a fully deuterated tetrahydrofuran-water ice clathrate. Three rotational excitations corresponding to J=0–1 transitions appeared near 14 meV in both energy gain and loss modes. Residual orthohydrogen at 5 K enabled unambiguous assignment of a J=1→0 transition. A doublet near 28.5 meV was attributed to J=1→2 transitions. A band at approximately 9 meV was identified as a translational quantum state transition, with additional broad features at 20, 25, 35, and 50–60 meV similarly assigned. Comparison with a five-dimensional quantum model for the SII clathrate dodecahedral cage revealed overestimation of the external potential and poor agreement for translational transitions. Among three analytically solvable models, the particle-on-a-sphere model provided the best match, consistent with quantum chemistry findings showing that the cage center is energetically unfavorable, producing shell-like confinement of the hydrogen wave function. These findings underscore the importance of translational quantum effects in confined hydrogen systems.
Within the dodecahedral clathrate cage, the central region is energetically unfavorable, causing the hydrogen molecule wave function to adopt a shell-like distribution and making translational quantum effects dominant over classical dynamics.
The delivery route is not clearly identifiable from this paper. For hydrogen intake, inhalation is the most efficient route; inhalation, however, carries explosion risk (empirical LFL of 10%; high-concentration devices are not recommended).
See also:
https://h2-papers.org/en/papers/17919035