Detrapping aspects of ripplonic polarons on a liquid helium film

Abstract

The problem of two-dimensional electron detrapping from the polaron to the quasifree state above a liquid helium film is studied employing the actual dispersion form of media vibrations. In contrast with the frequently used cutoff approximation, the actual form is shown to result in continuous and quite smooth changes of the polaron energy and mass near the detrapping point. At the same time, the electron localization radius (L) is found to increase rapidly, when the coupling constant $({\ensuremath{\alpha}}_{\mathrm{CC}})$ approaches unity: $L\ensuremath{\propto}({\ensuremath{\alpha}}_{\mathrm{CC}}\ensuremath{-}{1)}^{\ensuremath{-}1/2}\ensuremath{\rightarrow}\ensuremath{\infty}.$ In the framework of the general stability analysis, this electron detrapping is explained to be a result of an interesting relationship between the stability index and ${\ensuremath{\alpha}}_{\mathrm{CC}}$ for the media excitations involved in the polaron cloud.