Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 15: Postersitzung (Adsorption an Oberfl
ächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Rastersondentechniken, Zeitaufgelöste Spektroskopie, Methoden)

O 15.73: Poster

Friday, March 4, 2005, 17:00–20:00, Poster TU D

Electron coincidence spectroscopy on Xe/Cu(111) — •Carsten Winkler and Jürgen Kirschner — MPI f. Mikrostrukturphysik, Weinberg 2, D-06120 Halle

Correlation between electrons is a fundamental characteristics of systems containing many electrons. In the present experiments, electron coincidence spectroscopy (e,2e) has been carried out in order to study energy distributions of correlated electrons ejected from condensed Xe films. The films have been prepared by dosing 20 L of Xe onto a Cu(111) single crystal surface that was cooled down by ℓHe to a temperature of T_p ≃ 50 K. The incoming (primary) electrons are generated by a pulsed electrom source with a kinetic energy in the range of 20 eV ≤ E_p ≤ 35 eV. The scattered (secondary) coincidend electrons, on the other hand, are detected by using two reflection time-of-flight (TOF) spectrometers. With that, the kinetic energies E₁ and E₂ of the corresponding coincident electrons can be calculated from its flight time from sample the to the detector.

As a first step, TOF spectra were taken for Xe adsorbed on Cu(111) at energies of E_p= 20 eV and E_p= 25 eV. Compared to the corresponding data of metals like Cu or Co, these measurements show rather high coincidence count rates. The data generally show a distinct feature in the region (E₁ + E₂) = E_p − W with E₁ = E₂. Here, W is the work function that was determined to be W ≃ 8 eV. These promising results of the very first (e,2e)-coincidence studies on solid Xe are an encouragement for further systematic investigations, namely varying the Xe film thickness. (2004)