Mobility of Electrons on the Surface of Liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$

The mobility of electrons on the surface of liquid ${}_{}{}^4{}_{}{}^{}\mathrm{He}$ has been measured from 0.9 to 3.2°K. Although scattering from atoms in the vapor appears to be the dominant scattering mechanism, the mobility of the surface electrons is significantly lower than that of free electrons in the vapor. No evidence for surface-wave scattering is discernible.