Direct observation of a Feshbach-type electron resonance in solid argon

Abstract

We show from high-resolution electron-scattering experiments on multilayer Ar films that an electron resonance occurs at 11.8 eV in solid Ar and decays by releasing a substantial amount of energy (0.5--1 eV) to the lattice. This resonance, which lies slightly below the lowest bulk exciton energy, is identified as a Feshbach resonance. Its lifetime is estimated to be 2.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}14}$ sec from a semiclassical analysis of the multiphonon electron-energy-loss data.