Third sound and NMR studies of helium mixtures in nuclepore

We report measurements of the third sound properties of {sup 3}He-{sup 4}He mixture films on Nuclepore. Using third sound resonance techniques, we measure the frequency, damping, amplitude and phase of third sound modes on a mixture film with a fixed coverage of {sup 4}He, n{sub 4 } = 0.39{angstrom}{sup -2}, as a function of drive power, P{sub dr}, 0.044 {le} P{sub dr} {le} 440 nW, temperature, 40 {le} T {le} 500 mK, and {sup 3}He coverage, 0.01 {le} n{sub 3} {le}0.06{angstrom}{sup -2}. Near T = 200 mK there is a sharp shift in the difference in phase, {delta}{Phi}, between the drive voltage fluctuation and the film thickness fluctuation.