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 27.88: Poster
Dienstag, 24. März 2009, 18:30–21:00, P2
Improved determination of the IMFP by extracting the optimum loss function from EELS — •Tina Graber1, Frank Forster1, Achim Schöll1, and Friedrich Reinert1,2 — 1Universität Würzburg, Experimentelle Physik II, Am Hubland, 97074 Würzburg — 2Gemeinschaftslabor für Nanoanalytik, Forschungszentrum Karlsruhe, 76021 Karlsruhe
A precise knowledge of the inelastic mean free path (IMPF) of electrons in matter is of crucial interest in many respects. If electron spectroscopic techniques are applied in surface and interface science, the attenuation length of the involved electrons has to be established in order to gain information on, e.g., probing depth, adsorbate film thickness, or growth modes. In this work we present a systematic study on the IMFP of electrons in thin films of organic molecules by means of photoelectron spectroscopy (PES) and using the model system PTCDA/Ag(111). This system can be carefully controlled for a precise determination of the IMFP since layer-by-layer growth is necessary. Moreover, an appropriate description of the PES background is needed. For this purpose electron energy loss spectroscopy (EELS) provides valuable information on the relevant loss mechanisms. From the EELS data the optimum loss function can be determined. This loss function was subsequently applied for a Tougaard description of the PES background using the QUASES software[1]. In addition, the dependence of the IMFP on the emission angle has been investigated in order to find evidence for scattering channels or favored emission angles. [1] S. Tougaard, Software Package, Vers. 5.1 (2005)