Energy of the excess electron in methane and ethane near the critical point

Field ionization measurements of trimethylamine in methane and triethylamine in ethane are presented as a function of perturber number density at various noncritical temperatures and near the perturber critical isotherm. Critical point efiects are observed that are similar to those seen in atomic ∞uids. A two-Yukawa potential is shown to model the perturber/perturber interactions accurately by calculating the phase diagram of the perturber ∞uids, and using this potential the local WignerSeitz model for the energy of the excess electron is successfully applied to these molecular systems.