Berlin 2015 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 3: Inorganic/Organic Interfaces: Growth I

O 3.3: Vortrag

Montag, 16. März 2015, 11:00–11:15, MA 005

Potassium doping of ultrathin layers of coronene on Ag(111) — •Tobias Huempfner, Falko Sojka, Roman Forker, and Torsten Fritz — Friedrich Schiller University, Institute of Solid State Physics, Helmholtzweg 5, 07743 Jena, Germany

We report on the influence of potassium doping on ultrathin coronene layers in the (sub-) monolayer regime on Ag(111). The film growth and doping are successively traced in situ via differential reflectance spectroscopy (DRS) [1,2]. During the doping process the formation of a primary phase and, subsequently, of monoanions and dianions was observed by comparing the measured data to solution spectra [3]. After stopping the potassium deposition the dianions decay into monoanions and into molecules in the primary phase. The two latter species are stable and could be further investigated structurally and electronically via low energy electron diffraction (LEED) and scanning tunneling microscopy / spectroscopy (STM, STS). Besides the already known structure for one monolayer (ML) of undoped coronene on Ag(111) a new epitaxial structure is found for a coverage below 1 ML. Although the doped molecules do not show any highly ordered structure, they could be identified via STM measurements. While the potassium atoms are not resolved in the STM images, the doping process is evidenced by characteristic features in the related STS data.

References: [1] R. Forker et al., Annu. Rep. Prog. Chem., Sect. C: Phys. Chem. 108, 34-68 (2012). [2] R. Forker and T. Fritz, Phys. Chem. Chem. Phys. 11, 2142-2155 (2009). [3] G. J. Hoijtink, Mol. Phys. 2, 85-95 (1959).