Muon spin relaxation as a probe of potential carbon-based hydrogen absorbers

• Published in: Europhysics letters Vol. 65; no. 1; pp. 130 - 136
• Main Authors: Blach, T. P, Gray, E. MacA
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01-01-2004; EDP Sciences
• Subjects: 76.75.+i; 81.05.Uw; 82.75.-z
• ISSN: 0295-5075; 1286-4854
• DOI: 10.1209/epl/i2003-10054-x

Literature reports of hydrogen absorption by nanostructured carbons range from nothing to tens of weight percent. We studied pristine graphite and two potassium-graphite intercalation compounds (GICs) using muon spin relaxation (μSR), because the positive muon is expected to behave like a light hydrogen isotope. The graphite did not trap muons, but at low temperatures a component of the μSR spectrum from the two GICs could only be modelled by the Kubo-Toyabe function. This result demonstrates that muons were trapped by these samples and implies that $\chem{H}$ atoms would also be localised in these traps, in qualitative agreement with accepted hydrogen absorption results. Thus μSR is confirmed to be a valuable probe of the relative ability of carbon-based samples to bind hydrogen atoms.