THE BINDING OF ALKALI ATOMS TO THE SURFACES OF LIQUID-HELIUM AND HYDROGEN

AIkali atoms have been shown previously to have only unstable binding states inside liquid He-4. We calculate the equilibrium configurations and binding energies of single alkali atoms near the liquid-vapor interface of He-4 and He-3. A simple interface model is used to predict the surface deformation due to the presence of the atoms. A more realistic density functional model yields somewhat higher energies in the case of He-4. For all alkali atoms, we find the surface binding energies to be around 10 to 20 K. A similar analysis with atom-H-2 interactions finds that alkali atoms tend to submerge into liquid H-2, with the exception of Li.