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Quantum delocalization of molecular hydrogen in alkali-graphite intercalates

Lovell, A; Fernandez-Alonso, F; Skipper, NT; Refson, K; Bennington, SM; Parker, SF; (2008) Quantum delocalization of molecular hydrogen in alkali-graphite intercalates. PHYS REV LETT , 101 (12) , Article 126101. 10.1103/PhysRevLett.101.126101. Green open access

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Abstract

The adsorption of molecular hydrogen (H-2) in the graphite intercalation compound KC24 is studied both experimentally and theoretically. High-resolution inelastic neutron data show spectral features consistent with a strong pinning of H-2 along a single axis. First-principles calculations provide novel insight into the nature of H-2 binding in intercalates but fail to account for the symmetry of the H-2 orientational potential deduced from experiment. The above discrepancy disappears once the H-2 center of mass is allowed to delocalize in the quantum-mechanical sense across three vicinal adsorption sites, naturally leading to the well-known saturation coverage of similar to 2H(2) per metal atom in this material. Our results demonstrate that H-2 storage in metal-doped carbon substrates can be severely affected by hitherto unexplored quantum-mechanical effects.

Type: Article
Title: Quantum delocalization of molecular hydrogen in alkali-graphite intercalates
Open access status: An open access version is available from UCL Discovery
DOI: 10.1103/PhysRevLett.101.126101
Publisher version: http://dx.doi.org/10.1103/PhysRevLett.101.126101
Language: English
Additional information: © 2008 The American Physical Society
Keywords: WALLED CARBON NANOTUBES, NEUTRON-SCATTERING, POTASSIUM-GRAPHITE, STORAGE, H-2, ADSORPTION, SPECTROMETER, SITE
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy
URI: https://discovery.ucl.ac.uk/id/eprint/136465
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