Quasi-free electron energy in near critical point helium

We present for the first time the quasi-free electron energy V0(ρ) in helium from low density to the density of the triple point liquid (gaseous helium/liquid helium I/liquid helium II triple point), on a noncritical isotherm and on an isotherm near the critical temperature. These data were obtained using field enhanced photoemission, a new experimental technique for the characterization of dense fluids. A novel critical point effect in helium is presented and is accurately fitted to the local Wigner–Seitz model. This model, which was developed for attractive fluids, is thereby shown to be applicable to repulsive fluids as well.