Liquid-Vapor Coexistence in Two-Dimensional 3He-4He Mixtures

We present results from an ongoing study of the Liquid (L)-Vapor (V) coexistence boundary for single layer mixtures of³He and 4He adsorbed on two layers of H₂plating graphite. We are studying mixtures with³He molar fractions, x, of approximately 0.05, 0.1, 0.35, and 0.5, which we compare with previously published data for the pure isotopes. For the concentrations under study, we have approximate determinations of the L- V critical temperatures and of the low temperature density of the condensed phase.