Energy of the quasi-free electron in CO and HD: Probing intermolecular potentials within the local Wigner-Seitz model

We present the quasi-free electron energy V₀(ρ) in the weakly polar fluids CO and HD from gas to liquid densities ρ, on noncritical isotherms, and at a temperature near the critical isotherm. These results represent the first systematic investigation of V₀(ρ) in polar fluids across a broad density range and illustrate that field enhanced photoemission can be used to obtain data in such systems. We show that the local Wigner-Seitz model for V₀(ρ), when coupled with thermodynamic data for the fluids, can yield optimized intermolecular potential parameters, as well as the magnitude of the zero kinetic energy electron scattering length.