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Nanostrukturen und Grenzflächen Poster: Do., 13:00–15:30 D-P277
Absorption of π-conjugated molecules on Cu(111) and Ag(111)
Alexander Gerlach 1 , Stefan Sellner 1 , Frank Schreiber 1 , Norbert Koch 2 ,
Tien-Lin Lee 3 , Jörg Zegenhagen 3
1 Tübingen University, Institute for Applied Physics, 72076 Tübingen, Germany –
2 Humboldt University Berlin, Institute for Physics, Newtonstr. 15, 12489 Berlin, Germany
– 3 ESRF, Rue Jules Horowity 6, BP220, 38043 Grenoble, France
We study the adsorption of different aromatic molecules such as phthalocyanines and
perylene derivatives on Cu(111) and Ag(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 core-level 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 of the adsorbed molecules [1] that are related
to the charge (re)distribution at the interface, which can be discussed in terms of rehybridization.
We also discuss our approach of analyzing non-dipolar contributions to
the XPS signal [2]. Finally, we discuss recent attempts to determine the bending of
aromatic ring structures based on chemical shift in the XPS signal.
[1] A. Gerlach et al, Phys. Rev. B 71 (2005) 205425
[2] F. Schreiber et al., Surf. Sci. Lett. 486 (2001) 519