Elastische Streuung langsamer Elektronen an einem Bi-Atomstrahl

The angular distribution of electrons elastically scattered by bismuth atoms has been investigated in the angular range from 30 to 155° and with electron energies between 5 and 1200 eV. Theoretical data, which are available for energies above 100 eV, are in good agreement with experiment.     

Elastische und unelastische Streuung von Elektronen an Gasen

The theoretical differential cross section for the elastic scattering and for the excitation of optical transitions in helium by electron impact has been refined in Born approximation by use of the two parameter Eckart eigenfunction for the ground state and for the excited states. The angular distributions of 25 kev electrons scattered elastically and inelastically by helium were measured in the angular range 2·3·10^?4≦?≦4·10^?2. The intensity distribution of the elastically scattered electrons is in accordance with the theoretical curve for?>7·10^?3 and is disturbed at smaller angles by the primary beam. Normalization of the experimental values to the theoretical elastic differential cross section leads to agreement between the experimental differential cross section for the excitation of the 2¹ P and 3¹ P state and the scattering formulae given in this paper. There are small systematic deviations (<20%) for the 2¹ P differential cross section in the angular range 3·10^?3<?<1·10^?2 only. The oscillator strength of these two transitions has been determined from the scattering measurements:f ₂₁=0·312±0·04 andf ₃₁=0·0898±0·006.     

Messung charakteristischer Energieverluste von Elektronen an leichtoxydierbaren Metallen im Ultrahochvakuum

Energy losses of 34 keV electrons penetrating thin foils of Li, Na, K, Rb, Cs, Ca, Sr, Ba, Mg, and Al are measured. The metals are evaporated and investigated in UHV (~10^-9 Lorr) with an apparatus constructed especially for this purpose. For all the alkali metals free electrons like behaviour is found with a surface and a volume plasma loss. Ca and Sr show more complicated structures. For most of the volume losses half width, dispersion and cut-off is measured. Surface losses are investigated for oxide-free surfaces with respect to angular distribution, dispersion and total excitation probability, and also the displacement due to oxidation is measured. A narrow loss line from the excitation of a surface wave at the Al/Mg interface is found at 12.8 eV in good agreement with the theoretically predicted value.     

Berechnung der Energieverluste schneller Elektronen in dünnen Schichten mit Retardierung

Regarding the retardation of the electromagnetic field, a semiclassical formula for the energy-loss-probability of fast electrons penetrating a thin foil with a dielectric constant?=?(Ω) is derived. This formula is discussed for the special cases of the free electron gas and the occurence of Cerenkov-radiation in substances with high dielectric constants. Numerical evaluations have been made for these cases. Significant deviations from the formula without retardation are found, which are confirmed by the experiments.     

Über den Einfluß der Oberflächen dünner Schichten auf die Energieverluste schneller Elektronen in Al

Zeitschrift für Physik A Hadrons and nuclei - The Schrieffer-Wolff transformation which connects the Anderson and Kondo models of a magnetic impurity is studied for the case of several...     

Energieverluste von 50 keV-Elektronen an Ge und Si

Electron-Energy loss spectra of Ge and Si (amorphous, polycristalline and monocristalline) are measured in the low energy region of the band-band transitions and in the energy region of the plasma losses. These spectra are compared with the loss curve calculated from optical data: Discrepancies in the absolute values of the height and in the width of the plasma losses are found; the structures of the region of the bandband excitations show an agreement in the positions of the maxima, but not in their height. Additional electron energy loss maxima are observed.