Nuclear spin–lattice relaxation of ³He on neon surfaces

Abstract

Measurements have been made of the NMR wall relaxation time, T 1W , of a system of 3 He gas in contact with a strongly relaxing untreated pyrex surface and also a weakly relaxing neon-coated pyrex cell. The experiments were performed at temperatures in the range 2.6 K < T < 20 K and at fields between 0.5 and 9.3 kG. The field dependence of T IW for the weakly relaxing neon surfaces can be understood in terms of a model of a surface layer of adsorbed 3 He atoms. A theory of relaxation governed by the two-dimensional diffusion of 3 He atoms is presented and found to give a satisfactory fit to the data. The experiments suggest that measurements of the gas phase 3 He relaxation times T 1 are an effective and useful probe of the adsorbed phase of 3 He.