Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 44: Metal Substrates: Structure, Epitaxy and Growth

O 44.4: Poster

Dienstag, 21. März 2017, 18:30–20:30, P1A

Comparison of tin(II)- and lead(II)-phthalocyanine layers adsorbed on 1 ML PTCDA/Ag(111) — •Philipp Mueller, Marco Gruenewald, J. Peuker, F. Sojka, Roman Forker, and Torsten Fritz — Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 5, 07743 Jena, Germany

We investigate the growth of ultrathin, highly ordered layers of the shuttlecock-shaped molecules tin(II)-phthalocyanines (SnPc) and lead(II)-phthalocyanines (PbPc) on top of one monolayer 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) on Ag(111). The films have been characterized structurally by means of low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) as well as optically using differential reflectance spectroscopy (DRS). We find that neither their lateral structures formed nor their fingerprints in optical absorption allow distinguishing between both molecules when they are adsorbed on 1 ML PTCDA/Ag(111). In fact, the condensed phases of both systems yield the same commensurate registries with respect to PTCDA. Even the structures formed for higher film thicknesses are rather similar. Also their fingerprints in optical absorption are almost identical. Here we report a possibility of distinguishing both molecules in the respective monolayer phases by means of their different STM-tip-induced switching behavior: SnPc can easily be switched from Sn-down to Sn-up configuration and vice versa by applying tip voltage pulses, whereas PbPc did not respond to our switching attempts. This provides one method of chemical identification on the molecular scale.