The energy of the quasi-free electron in near critical point nitrogen

► Field enhanced photoemission (FEP) is used to measure V0(ρ) in N2. ► V0(ρ) in N2 from low density to the density of the triple point liquid is obtained for the first time. ► A critical point effect in V0(ρ) in N2 observed and analyzed. ► The local Wigner-Seitz approach is shown to model V0(ρ) in N2.