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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.19: Poster

Dienstag, 15. März 2011, 18:30–22:00, P4

Tuning the energy level alignment at the SnPc/Ag(111) interface using an STM tip — •Marius Toader and Michael Hietschold — Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group, D-09107 Chemnitz, Germany

The tip influence on the energy level alignment at the SnPc/Ag(111) interface has been addressed via the Scanning Tunneling Spectroscopy (STS). A collective effect characteristic for both molecular conformations up and down is reported to shift the corresponding first filled (HOMO) and empty (LUMO) levels towards the Fermi energy via a tip-sample distance decrease. The importance of the tin ion coupling to the metal electrodes is emphasized for the newly reported cross-bending (cross-shifting) effect. The observation is proven to be driven by the bistable donor/acceptor character of the SnPc molecules. Distinct types of coupling to the metal surface have been found for the two molecular conformations. However, a similar adsorption geometry of the molecular plane is emphasized by the same energy position of the HOMO level. Moreover, the crucial importance of the HOMO-1 (found using DFT to show strong contribution from the Sn ion) for a conformational change is proven via a controllable and irreversible tip-induced single-molecule switching and nano-writing within densely packed molecular arrays.