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.