Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 43: Poster Session II - MA 141/144 (Surface Spectroscopy on Kondo Systems; Frontiers of Surface Sensitive Electron Microscopy; Methods: Scanning Probe Techniques+Electronic Structure Theory+Other; Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation; joined by SYNF posters)
O 43.34: Poster
Dienstag, 26. Februar 2008, 18:30–19:30, Poster F
Positron annihilation induced Auger electron spectroscopy on Si single crystals — •Jakob Mayer1, Klaus Schreckenbach1,2, and Christoph Hugenschmidt1,2 — 1Technische Universität München, Physikdepartment E21, James-Franck-Str., 85748 Garching — 2ZWE FRM II, Lichtenbergstr.1, 85747 Garching
Positron annihilation induced Auger electron spectroscopy (PAES) is a powerful technique for the element selective investigation of surfaces. Due to the different hole creation process compared to conventional EAES, i.e. ionisation by means of positron electron annihilation instead of collision, the impact energy of the positrons can be chosen very low and hence the secondary electron background ends at this low energy. Furthermore only the topmost atomic layer is examined, due to the positron diffusion back to the surface. The main challenge in PAES is the low positron current, which is on the order of pA. Even at the high intensity positron source NEPOMUC at the FRM II the measurement times are on the order of hours. In order to reduce the acquisition time a new electron energy analyser with a higher efficiency has been installed. First measurements on polycrystalline Cu and Si single crystals will be presented and compared to previous measurements.