Total cross sections for slow-electron (1–20 eV) scattering in solidH2O

Abstract

An analytical method is proposed to determine absolute total cross sections per scatterer and related mean free paths for low-energy electron scattering in disordered molecular solid films. The procedure is based on a two-stream multiple-scattering model of the thickness dependence of the film reflectivity for elastic electrons. The expected analytical behavior and accuracy are tested on a model sample whose scattering properties are generated by a Monte Carlo simulation from initially known parameters. The effects of multiple scattering inside the film and at its interfaces are taken into account and discussed. The thickness dependence of the elastic electron reflectivity of ${\mathrm{H}}_2$O film condensed at 14 K is reported between 1 and 20 eV incident energy with a spectrometer resolution of 10 meV. The proposed method is applied to extract from these measurements the energy dependence of the total effective and total inelastic cross sections for electron scattering in amorphous ice.