Regensburg 2004 – wissenschaftliches Programm
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O: Oberflächenphysik
O 14: Postersitzung (Adsorption an Oberflächen, Epitaxie und Wachstum, Organische Dünnschichten, Oxide und Isolatoren, Phasenübergänge, Rastersondentechniken, Struktur und Dynamik reiner Oberflächen)
O 14.58: Poster
Montag, 8. März 2004, 18:00–21:00, Bereich C
Normal Incidence X-ray Standing Waves (NIXSW) study of PTCDA on Ag(111) — •A. Hauschild1, M. Sokolowski1, and F. S. Tautz2 — 1Institut für Physikalische und Theoretische Chemie , Universität Bonn, Wegelerstr. 12, 53115 Bonn, Germany — 2School of Engineering and Science, International University Bremen, PO Box 750561, 28725 Bremen, Germany
Whereas the adsorption geometries of small molecules on surfaces are already rather well understood up to now, only little information has been gained for larger aromatic molecules so far, partly because of experimental reasons.
PTCDA (3,4,9,10-perylene-tetracarboxylicacid-dianhydrid) chemisorbs on Ag(111) substrate, forming a commensurate monolayer with flat lying molecules arranged in a so-called No-dqherringbone-patternNo-dq. We have investigated the atomic bonding distances of PTCDA relative to the Ag(111) by NIXSW measurements performed on the O1s and C1s level. Since oxygen and carbon are light atoms, the analysis requires taking into account non-dipolar contributions to the photoemission yield. First results indicate an averaged bonding distance for the oxygen atoms of 2.84 Å and for the carbon atoms of 2.90 Å.
This work was performed in cooperation with C. Stadler, C. Kumpf and E. Umbach (Universität Würzburg) and supported by the ESRF (Grenoble, France).