Dresden 2003 – wissenschaftliches Programm

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O: Oberflächenphysik

O 10: Elektronische Struktur II

O 10.9: Vortrag

Montag, 24. März 2003, 17:00–17:15, FOE/ORG

Vacuum Electron Interferometry — A Novel Approach to Study Surface Electronic Structure with the STM — •Martin Hansmann, Gustavo Ceballos, José I. Pascual, Lucía Aballe, Hans-Peter Rust, and Karsten Horn — Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin

Usually, a scanning tunneling microscope (STM) probes bound occupied or unoccupied electronic states of a sample, depending on the bias voltage. If the (positive) sample bias exceeds the vacuum level, this is no longer the case but electrons coming from the tip are partially reflected at the sample surface and again at the tunneling barrier. They are confined by the electric potential between tip and sample, giving rise to a discrete series of quantum well states [1]. The corresponding field states can be observed with the STM. The position and shape of the resonances contain information on the phase shift and reflection of the electron waves which can be extracted using a simple one-dimensional model [2]. Here, we use this information to study the electronic structure of the Cu(100) surface above the vacuum level. Moreover, a careful analysis of spectroscopic maps leads to a qualitative understanding of the lateral behavior, i.e. parallel to the surface, of the field state electrons due to the local surface structure.

[1] G. Binnig et al., Phys. Rev. Lett. 55, 991(1985)

[2] A. Caamaño et al., Surf. Sci. 426, L420(1999)