Martin Luther University Halle-Wittenberg

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Diploma Thesis

Dispersion Relation of Image Potential States

The aim of this work was to investigate theoretically the measurement of the dispersion relation of image potential states. Image potential states are quasi discrete ones which are induced by the field of a tunnel tip above a surface. Electrons can tunnel resonant through these states which makes a spectroscopy of these states with measurements of the distance on voltage characteristic z(V) and differential conductivity voltage characteristic possible.

The dispersion relation of image potential states describes the behaviour of these states parallel to the surface. This can be measured with the help of a combination of scanning tunnel spectroscopy and scanning tunnel microscopy.

To describe such experiments a two-dimensional model for the tunnel process between tip and surface was developed. By the assistance of this model both the different influences on the z (V) spectroscopy were examined and the measurement of the dispersion relation was simulated. The results received thereby supply explanations for the experimental findings.

Diploma Thesis (German)
diplom_fechner.pdf (1.9 MB)  vom 08.02.2010