Properties of the spherical 2D electron system in a multielectron bubble in liquid helium

Multielectron bubbles in liquid helium contain a spherical two-dimensional (2D) electron gas. By varying the number of electrons or the pressure on the bubble, the surface density of electrons can be varied over a much larger range than that available for a 2D electron gas on a flat helium surface. The existence of a ripplopolaron solid phase for pressurized bubbles is discussed, and results are presented on the effective mass and the energy of the ripplopolarons. The predicted Wigner lattice of ripplopolarons will melt by dissociation of the ripplopolarons, resulting in an spherical 2D electron gas. We investigate the direct and exchange contributions of the interaction energy in this state in the Hartree–Fock formalism.