Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Poster Session I (Methods: Scanning probe techniques; Methods: Atomic and electronic structure; Methods: Molecular simulations and statistical mechanics; Oxides and Insulators: Clean surfaces; Oxides and Insulators: Adsorption; Oxides and Insulators: Epitaxy and growth; Semiconductor substrates: Clean surfaces; Semiconductor substrates: Epitaxy and growth; Semiconductor substrates: Adsorption; Nano- optics of metallic and semiconducting nanostructures; Electronic structure; Methods: Electronic structure theory; Methods: other (experimental); Methods: other (theory); Solutions on surfaces; Epitaxial Graphene; Surface oder interface magnetism; Phase transitions; Time-resolved spectroscopies)

O 27.29: Poster

Dienstag, 24. März 2009, 18:30–21:00, P2

High-resolution electron gun for inverse photoemission — •Anna Zumbülte, Thomas Saerbeck, and Markus Donath — Physikalisches Institut, Westfälische Wilhelms-Universität Münster, 48149 Münster

Inverse photoemission (IPE) is an applied method to investigate the unoccupied part of the electronic structure above the Fermi level. The setup of such an experiment consists of an electron gun and a detection system for photons. A high energy and angle resolution is necessary for a k-resolved separation of as many electronic states as possible in the spectra. Therefore the improvement of the setup components is always an object. State-of-the-art setups achieve an energy resolution of about 150 meV and an angular resolution of 2^∘-5^∘ [1].

We present a spin-polarized electron gun with comparable energy resolution and an improved angular resolution. It consists of a GaAs photoemitter combined with a toroidal 90^∘ electrostatic deflector acting as monochromator. With this we achieve an energy resolution of 150 meV to 250 meV, depending on the current. Measurements of the beam profile indicate a low divergence that can be verified by IPE spectra of Cu (111). Here, the intensity ratio between the two surface states observed at normal incidence is an indicator of the angular resolution. In our case, measurements show a divergence smaller than 2^∘.

[1] M. Budke et. al., Rev. Sci. Instrum. 78, 113909 (2007)