NMR Relaxation of Adsorbed Gases: Methane on Graphite

Abstract
Spin‐lattice (T1) and spin‐spin (T2) relaxation times have been measured for methane (CH4) adsorbed on a graphitized carbon black, using pulse techniques at 30 MHz. Temperatures ranged from 4–100°K, fractional coverages from 0.02 to 0.9 of a statistical monolayer. The data indicate an adsorbed gas phase at high temperatures and low coverages and an adsorbed ``solid'' phase at low temperatures and low coverages. The data are discussed in terms of the molecular dynamics in the two phases and the barrier to rotation with respect to the surface.

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