Zur Dispersion der OberflÄchenplasmaverluste an reinen und oxydierten AluminiumoberflÄchen

The dispersion of the surface plasma oscillations is caused by

1. the coupling of the two surfaces of thin foils, that leads to a splitting into two modes of oscillation with different dependence of frequency on wavelength.
2. the influence of thin coating of e.g. oxide, that produces a displacement of the frequency depending on the wavelength of the surface oscillation.

Plasma oscillations were excited by 34 kV-electrons in thin foils of Aluminium vaporised on foils of Al₂O₃ in ultra-high vacuum. It was thus possible, to investigate oscillations of clean and oxidized Al-surfaces. By measurements of the energy loss as a function of the scattering angle of the exciting electrons both effects of dispersion could be demonstrated in good agreement with the theory. Also the influence of retardation was observed.