a Department of Physics, University of Exeter, Exeter, EX4 QL, UK
b Fakultät für Physik, Universität Konstanz, 78457 Konstanz, Germany
Abstract:
For pure 4He on Cs a nonwet phase exists below ≈2 K but for dilute 3He–4He mixtures the wetting is reentrant. Measurements of the contact angle with dilute mixtures of liquid helium on Cs can be explained in detail in terms of 3He states together with ripplons at the Cs–He mixture interface, but it is impossible to account for the lower wetting temperatures or contact angles with only 3He states or ripplons. We discuss the influence of surface roughness of the Cs on the contribution of interface excitations to the free energy and suggest that the variety of contact angles found with different samples of Cs is due mainly to their degree of roughness.