Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Molecular Films
O 88.8: Vortrag
Freitag, 15. März 2013, 12:15–12:30, H38
High Resolution Core-Level Spectroscopy of Molecular Switches at Silicon(111) Surfaces — •Daniel Przyrembel1, Michael Åxman Petersen2, Andreas Hebert2, Karola Rück-Braun2, and Martin Weinelt1 — 1Institut für Experimentalphysik, Freie Universität Berlin — 2Institut für Chemie, Technische Universität Berlin
Si(111) surfaces, functionalised with organic molecular switches of the fulgimide[1] and dihydroazulene[2] (DHA) type, have been investigated by means of high resolution X-ray photoelectron spectroscopy (XPS). The versatile anchoring strategy involves first the attachment of alkyl acid chains to the H-terminated Si(111) single crystal surface and second coupling of the molecular switches to these carboxyl linkers. This leads to very stable and durable self assembled monolayers (SAMs). The linker chain-density can be adjusted by mixing in inert alkyl chains. Thus the packing density of molecular switches becomes tuneable. All steps of the sample preparation have been monitored and their efficiency proven. Fulgimides are optically switchable between open and closed forms by irradiation with UV and visible light, DHA turns into its isomer vinyl heptafulvene (VHF) upon optical stimulation and reacts back thermally. The reversible switching of the molecules leads to small, reproducible modifications of the XP spectra, i.e. peak shifts and shape changes, only weakly affected by successive beam damage. A reduced packing density of molecular switches improves the switching efficiency. [1] Y. Yokoyama Chem. Rev. 2000, 100, 1717-1739; [2] J. Daub, T. Knöchel, A. Mannschreck Angew. Chem. 1984, 96, 980-981