Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 29: Organic-Inorganic Hybrid Systems and Organic Films IV

O 29.6: Vortrag

Dienstag, 21. März 2017, 11:45–12:00, WIL A317

Impact of collective electrostatics on XPS Spectra of organic adsorbate layers — •Thomas C. Taucher, Oliver T. Hofmann, and Egbert Zojer — Institute of Solid State Physics, NAWI Graz, Graz University of Technology, Austria

In this contribution we investigate the applicability of slab-type density functional theory-based band structure calculations to quantitatively model XPS core-level shifts at metal-organic interfaces. We compare the performance of the initial state approach (neglecting screening effects) and different variants of the final state approach (inherently considering screening) for the case of self-assembled monolayers of long, upright standing molecules. In particular we here discuss serious artifacts occurring when combining final state approaches with periodic boundary condition based calculations.

Beyond these more technical aspects, we also compare the relative impact of chemical shifts and binding energy shifts caused by collective electrostatic effects. The latter, albeit often overlooked, do play an important role for densely packed adsorbate layers consisting of molecules that bear polar elements.[1] In fact, electrostatic shifts of core-level binding energies pave a way for using XPS as a probe of local changes in the electrostatic energy in a sample.

[1] T. C. Taucher et al., J. Phys. Chem. C., 2016, 120, 6, 3428.