Density-dependent mobility of a two-dimensional electron fluid

Measurements of the low-frequency electron mobility on a helium surface are extended to higher densities and to lower temperatures than those previously reported in the literature. For electron areal densities greater than 5 × ${10}^7$ ${\mathrm{cm}}^{-2\mathrm{}}$, the electron scattering is greater than predicted by one-electron theories by an amount which is weakly temperature dependent and increases with increasing density.