Nuclear magnetic relaxation of helium-3 adsorbed on Mylar film

Pulsed NMR measurements on helium-3 adsorbed on Mylar film have been made at a Larmor frequency of 5 MHz for fractional monolayer coverages between 0.3 and 1. Relaxation times were measured at temperatures between 1.2 and 4 K for different orientations of the substrate plane with respect to the static magnetic field. Our results are consistent with a patchy solid model where approximately 0.1 of a monolayer remains relatively immobile, providing the relaxation mechanism, while the rest of the adsorbate remains fluid. We have no evidence for an abrupt transition of this fluid to a solid phase.