Electron scattering by highly polar molecules. I. KI

Abstract

Electron-impact energy-loss spectra of KI were studied experimentally in the 15\ifmmode^\circ\else\textdegree\fi{} to 130\ifmmode^\circ\else\textdegree\fi{} angular range at impact energies of 6.7, 15.7, and 60 eV. The spectra reveal a number of excitation features which have not been detected previously and indicate that KI is a strong photon absorber in the vacuum-uv region. From the spectra, differential and integral electronically elastic and inelastic cross sections have been obtained by normalizing the experimental data to theoretical results at low scattering angles. Rotational excitation cross sections corresponding to $\ensuremath{\Delta}j=0,\ifmmode\pm\else\textpm\fi{}1$ have been calculated using a dipole-plus-repulsive-core interaction potential and the distorted-wave approximation. For purpose of comparison, the rotational ($\ensuremath{\Delta}j=\ifmmode\pm\else\textpm\fi{}1$) excitation cross sections have also been calculated in the Born point-dipole approximation.