Precise determination of differential electron scattering cross sections. II. CH4, CO2, CF4

Abstract

Precise total (elastic plus inelastic) differential cross sections have been measured for CH4, CO2, and CF4 with 50.4 keV incident electrons. The accuracies are 0.1% in the intensities and ±2 arc sec in the scattering angles. The structure parameters have been evaluated. The bond distances agree well with previous results, although the mean amplitudes of vibration are in general larger than those calculated from harmonic force fields. The difference curves comparing the experimental cross sections to IAM (independent atom model) predictions are discussed utilizing CI atomic potentials in the IAM. The ’’binding’’ energies have been determined and are found to be consistently several electron volts above those evaluated via the heat of combustion.