New Stability Limit of Electrons Trapped on the Surface of Liquid Helium

We report the discovery of a density, $n$, and electric field, $E_p$, dependent critical temperature for electrons trapped on the surface of liquid helium for densities $n>\mathrm{}\frac{1.2E_p}{2\pi e}$. Above this critical temperature a finite fraction of the electrons escape rapidly from the surface into the vacuum. The critical temperature increases with decreasing density, for a given electric field.