Energy of the quasifree electron in argon and krypton

Field ionization measurements of CH3I and C2H5I dopant high-n molecular Rydberg states in argon and krypton perturbers are presented as a function of perturber number density along various isotherms up to the density of the triple point liquid. Using these data, a new local Wigner-Seitz model for the density-dependent energy V0(ρP) of a quasifree electron in argon and krypton is developed. This model, which contains only one adjustable parameter, uses a local Wigner-Seitz radius derived from the local number density rather than from the bulk number density, includes a statistical mechanical calculation of both the ion/medium polarization energy and the electron/medium polarization energy, and includes the thermal kinetic energy of the quasifree electron. Using this model, V0(ρP) and the perturber-induced energy shift of the dopant ionization potential ΔD(ρP) are calculated to within ±0.1% of experiment. Previously reported V0(ρP) data for xenon are also shown to be interpretable within this new model