Polaronic behavior of electrons on a liquid-helium film

Abstract
The motion of electrons parallel to the surface of a liquid-helium film on a sapphire substrate is described by a Fröhlich-type Hamiltonian of the polaron. The polaronic transition from the nearly free to a quasilocalized state is observed at a certain critical value of the film thickness. We have pointed out situations in which a dimple filled with several electrons could be trapped at the helium film.