Quasi-free electron energy in near critical point helium

► Field enhanced photoemission (FEP) is used to experimentally determine V0(ρ) in He. ► V0(ρ) in He from low density to the gas/liquid He (I)/liquid He (II) triple point is obtained. ► Critical point effect in V0(ρ) in He is presented for the first time. ► Local Wigner-Seitz approach, developed for attractive fluids, is shown to model V0(ρ) in He.