NMR OF ADSORBED HE-3 - SURFACE PHYSICS AT MILLIKELVIN TEMPERATURES

NMR techniques are used for the study of two-dimensional quantum syste ms, represented by He-3 physically adsorbed on Grafoil, an exfoliated form of graphite. A description of our high sensitivity and very low p ower continuous wave spectrometer yielding very good signal to noise r atios at millikelvin temperatures is given. The evolution of line shap es and relaxation times with areal density is discussed. Some results of NMR measurements on He-3 films adsorbed on Grafoil are presented in the last section: influence of substrate heterogeneities, Fermi liqui d properties, study of phase transitions in two dimensions and magneti sm in solid phases.