# Inelastic neutron scattering study of hydrogen in d(8)-THFD(2)O ice clathrate.
> 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


## Abstract

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.

### Mechanism

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.

## Bibliographic

- **Authors**: Tait KT, Trouw F, Zhao Y, Brown CM, Downs RT
- **Journal**: J Chem Phys
- **Year**: 2007 (2007-10-07)
- **PMID**: [17919035](https://pubmed.ncbi.nlm.nih.gov/17919035/)
- **DOI**: [10.1063/1.2775927](https://doi.org/10.1063/1.2775927)
- **Study type**: other
- **Delivery route**: not specified
- **Effect reported**: not assessed

## Delivery context

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).

## Safety notes

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:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)

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> **Cite as**: H2 Papers — PMID 17919035. https://h2-papers.org/en/papers/17919035
> **Source**: PubMed PMID [17919035](https://pubmed.ncbi.nlm.nih.gov/17919035/)