Effective mass of He3 impurities in He4 films

We calculate the effective mass of He3 impurity atoms in a film of liquid He4 atoms adsorbed to a substrate. The calculated effective mas of the He3 impurity shows a strong dependence on the structure of the underlying He4 film. When both the coupling of the He3 impurity to the background and to other He3 impurities are taken into account, our values agree well with recent experiments by Wang and Gasparini [Phys. Rev. B 38, 11 245 (1988)]. It is suggested that the Fermi-liquid contribution to the effective mass is experimentally obsrevable.