Charge transfer and polarization screening in organic thin films: phthalocyanines on Au(100) |
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Authors: | Daniel Kolacyak Heiko Peisert and Thomas Chassé |
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Institution: | (1) Institute of Physical and Theoretical Chemistry, University of Tübingen, Auf der Morgenstelle 8, 72076 Tübingen, Germany |
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Abstract: | Core hole screening effects at organic/metal interfaces were studied by core level X-ray photoemission spectroscopy (XPS),
X-ray excited Auger electron spectroscopy (XAES), and valence band ultraviolet photoemission spectroscopy (UPS). The comparison
of energetic shifts in XPS and XAES enables the estimation of electronic relaxation energy (screening ability). Magnesium
phthalocyanine (MgPc) and zinc phthalocyanine (ZnPc) evaporated on single crystalline Au(100) were used as model molecules.
Two different features in the Mg KLL spectra can be clearly separated for (sub-)monolayer coverages, while only minor changes
of the shape of Mg 1s are observed. Applying a dielectric continuum model, the major screening mechanism cannot be described
sufficiently by polarization screening due to mirror charges, significant contributions by charge transfer screening have
to be considered. In contrast, small screening effects in the bulk material can be explained by surface polarization. |
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Keywords: | PACS" target="_blank">PACS 72 80 Le 79 60 Fr 73 20 -r |
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