  The properties of ripplonic polarons in a multielectron bubble in liquid
helium are investigated on the basis of a path-integral variational method. We
find that the two-dimensional electron gas can form deep dimples in the helium
surface, or ripplopolarons, to solidify as a Wigner crystal. We derive the
experimental conditions of temperature, pressure and number of electrons in the
bubble for this phase to be realized. This predicted state is distinct from the
usual Wigner lattice of electrons, in that it melts by the dissociation of the
ripplopolarons, when the electrons shed their localizing dimple as the pressure
on the multielectron bubble drops below a critical value.
