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O: Fachverband Oberflächenphysik

O 98: Metal and Semiconductor Substrates: Adsorption and Reactions of Small Molecules

O 98.2: Vortrag

Freitag, 21. März 2025, 10:45–11:00, H8

Adsorption sites of merocyanines on the Ag(100) surface determined by NIXSW — •Anna Juliana Kny¹, Anja Haags², Sergey Subach², and Moritz Sokolowski¹ — ¹Clausius Institut für Physikalische und Theoretische Chemie, Universität Bonn, Germany — ²Forschungszentrum Jülich, Germany

The growth of thin organic layers is strongly influenced by the interactions between the molecule and the substrate surface. We report about the adsorption sites of a series of merocyanine (MC) molecules on the Ag(100) surface. MCs are prochiral donor-acceptor molecules which are in focus for applications due to high transition dipole moments. [1] Remarkably, SPA-LEED data reveal commensurate structures for all of our investigated MCs, although the size of the unit cells depends on the length of the alkyl side chains.[2] In order to answer the question of what is behind the commensurate growth of these complex molecules, we performed an XPS and an NIXSW investigation. We find a strong binding of the two sulfur heteroatoms, located in the thiophene and the thiazole rings, to the Ag surface. This can be seen in charge transfer and an adsorption of the S-atoms close to on-top sites. This is found for all investigated structures. Furthermore, compatible with the symmetry of the unit cell, the results reveal that the four molecules per unit cell sit on two different adsorption sites.

We acknowledge experimental support from D.A. Duncan (DLS). Supported by the DFG through the research training group 2591 and the Diamond Light Source, UK.

[1] JACS 137 (2015) 13524. [2] Nanoscale 15 (2023) 10319.

Keywords: XPS; NIXSW; organic adsorbates; adsorption sites; SPA-LEED