AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS1-TuA

Paper SS1-TuA3
Binding Distances of Pi-conjugated Molecules on Cu(111) Studied by X-ray Standing Waves

Tuesday, November 14, 2006, 2:40 pm, Room 2002

Session: Surface Structure and Morphology
Presenter: A. Gerlach, Universität Tübingen, Germany
Authors: A. Gerlach, Universität Tübingen, Germany
F. Schreiber, Universität Tübingen, Germany
S. Sellner, Universität Tübingen, Germany
N. Koch, Humboldt University, Germany
T.-L. Lee, ESRF, France
J. Zegenhagen, ESRF, France
Correspondent: Click to Email
Although the binding distances are very fundamental parameters, it is remarkable how little is known about these for most organic semiconductors on metal contacts. We study the adsorption of different aromatic molecules such as phthalocyanines, perylene derivatives, and oligoacenes on Cu(111) using the X-ray standing wave (XSW) technique. Element specific structural information of high precision is derived from the analysis of XSW yield measurements. Using the C(1s), N(1s), and F(1s) photoelectron signals we show that the molecules adsorb in a lying-down configuration, but with different distances relative to the metal substrate. The binding distances between the aromatic ring structure and the metal substrate are generally found to be larger than covalent bond lengths. Furthermore, we discuss more subtle effects as e.g. deformations@footnote 1@ of the adsorbed molecules that are related to the charge (re)distribution at the interface, which can be discussed in terms of rehybridization. Finally, we discuss recent attempts to determine the bending of aromatic ring structures based on chemical shift in the XPS signal. @FootnoteText@ @footnote 1@ A. Gerlach et al, Phys. Rev. B 71 (2005) 205425.