Regensburg 2010 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 10: Poster I
MA 10.10: Poster
Dienstag, 23. März 2010, 10:45–13:45, Poster A
Stability of Mn6Cr single-molecule-magnets adsorbed on surfaces: The influence of X-ray exposure, layer thickness, choice of substrate and counterions — •Andreas Helmstedt1, Aaron Gryzia1, Sebastian Steppeler1, Norbert Müller1, Marc D. Sacher1, Ulrich Heinzmann1, Veronika Höke2, Thorsten Glaser2, Mikhail Fonin3, and Ulrich Rüdiger3 — 1Fak. f. Physik, Uni Bielefeld — 2Fak. f. Chemie, Uni Bielefeld — 3Fak. f. Physik, Uni Konstanz
The single-molecule-magnet (SMM) Mn6Cr consists of three main components: Two bowl-shaped Mn3-salen complexes are bridged by a complex containing one Cr atom. Three counterions are coupled to the triply charged SMM to ensure charge neutrality. Mn6Cr-SMM have a low stability against X-ray exposure, which adversely affects a study of the electronic properties by X-ray absorption- and photoelectron spectroscopy. With increasing exposure time, the spectral features of trivalent Mn representing intact molecules disappear while Mn(II)-typical features increase. This degradation process and its dependence on the photon flux, the substrate and the SMM concentration were observed during beamtimes at BESSY II and MAXLAB III. The rate of degradation shows also a strong dependence on the choice of counterions. The choosen preparation method allows the adsorption of Mn6Cr-SMM with varying layer thickness on various substrates. This study reveals an influence of the substrate and the molecule layer thickness on the initial electronic state of the adsorbed molecule layer, i.e. the molecules seem to degrade already during the adsorption process.
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