Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Electronic Structure of Surfaces II

O 58.10: Vortrag

Mittwoch, 18. März 2015, 17:15–17:30, MA 041

Investigation of the surface of binary metallic alloys using PAES, XPS and STM — •Samantha Zimnik, Christian Piochacz, Sebastian Vohburger, and Christoph Hugenschmidt — Heinz Maier-Leibnitz Zentrum (MLZ) and Physik Department E21, Technische Universität München, Lichtenbergstraße 1, 85748 Garching, Germany

The characterization of the elemental composition of surfaces is of high importance for the understanding of many surface-related processes such as catalysis or oxidation. However, surface segregation causes changes in the elemental constitution of the surface, which affects significantly the macroscopic properties of the system. Therefore, e.g. in the system Fe/Pt, it is of great interest to investigate the theoretically predicted surface segregation process.
Positron annihilation induced Auger Electron Spectroscopy (PAES) is a powerful technique to gather information about the elemental composition of only the topmost atomic layer of a specimen. The positron beam facility NEPOMUC delivers a high intensity positron beam of 10⁹e⁺/s and enables measurement times of only a few minutes per PAES spectrum. Thus, time-dependent PAES became possible and enables the in-situ observation of surface segregation processes. The upgraded surface spectrometer at NEPOMUC uses the complementary techniques PAES, XPS and STM for a comprehensive surface analysis. First temperature-dependent measurements on binary alloys are presented. Financial support by the BMBF (project no. 05K13WO1) is gratefully acknowledged.