Resonance Potentials in Thin Films of Potassium Chloride

Experiments have been conducted in which potassium chloride films have been bombarded with slow electrons. Electron absorption and backscattering were studied as a function of bombarding energy. Discontinuities of slope were obtained at characteristic bombarding energies, and these were interpreted in terms of decomposition and excitation energies. Three different experimental arrangements were utilized; a triode with a rotating dynode in which the electrons describe a simple straight-line path from source to target to detector, a device wherein both the primary and backscattered electron beams followed a cycloidal path due to external magnetic field, and an apparatus containing a magnetic velocity analyzer to limit the energy spread of the primary beam. General agreement was found in the data regardless of the type of apparatus used. The work function for inserting an electron into the potassium chloride film was estimated to be in the neighborhood of 0.3 ev.It has been suggested that the technique of slow-electron bombardment may be used as a tool for analysis in thin-film studies and as a means of identifying band structure.