We have measured the contact angle, Θ, of ${}_{}{}^3{}_{}{}^{}\mathrm{-}_{}^4{}_{}{}^{}$He mixtures on Cs and its temperature dependence together with the lower wetting transition temperatures of the reentrant behavior. We have obtained the difference in interface energies, ${\mathrm{\sigma }}_{\mathrm{Cs},\mathit{v}}$-${\mathrm{\sigma }}_{\mathrm{Cs},\mathit{l}}$, as a function of temperature. The results can be explained on the basis of a two-dimensional layer of ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at the Cs-He interface as well as on the free surface. The bound state energy of the ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ at the interface is -(2.2±0.1) K relative to ${}_{}{}^3{}_{}{}^{}\mathrm{He}$ in liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ and the effective mass is (1.55±0.1) ${\mathit{m}}_3$. Both the energy and effective mass are near the calculated values. © 1996 The American Physical Society.

• Received 10 June 1996

DOI:https://doi.org/10.1103/PhysRevB.54.7350