Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 42: Poster Session II (Nanostructures at surfaces: arrays; Nanostructures at surfaces: Dots, particles, clusters; Nanostructures at surfaces: Other; Nanostructures at surfaces: Wires, tubes; Metal substrates: Adsorption of O and/or H; Metal substrates: Clean surfaces; Metal substrates: Adsorption of organic/bio moledules; Metal substrates: Solid-liquid interfaces; Metal substrates: Adsorption of inorganic molecules; Metal substrates: Epitaxy and growth; Heterogeneous catalysis; Surface chemical reactions; Ab-initio approaches to excitations in condensed matter; Organic, polymeric, biomolecular films– also with adsorbates; Particles and clusters)
O 42.125: Poster
Mittwoch, 25. März 2009, 17:45–20:30, P2
Exposure of Single-Molecule-Magnets Mn6Cr and Mn7 to Soft X-Rays — Fabian Merschjohann1, •Andreas Helmstedt1, Aaron Gryzia1, Andreas Winter1, Sebastian Steppeler1, Norbert Müller1, Armin Brechling1, Marc D. Sacher1, Ulrich Heinzmann1, Carl-Georg Freiherr v. Richthofen2, Thorsten Glaser2, Sönke Voss3, Mikhail Fonin3, and Ulrich Rüdiger3 — 1Fak. f. Physik, Uni Bielefeld — 2Fak. f. Chemie, Uni Bielefeld — 3Fak. f. Physik, Uni Konstanz
Mn6Cr and Mn7 are two representatives of the new 7-core Single-Molecule-Magnets (SMM) with a large spin moment. Adsorbed on surfaces their electronic configuration may change depending on the substrate material. Possible modifications of the electronic configuration can be studied element-specificly by X-ray absorption spectroscopy and by measuring the spin-polarization of photoelectrons ejected by circularly polarized synchrotron radiation. Drawback of the above mentioned methods is the bad stability of the SMM during X-ray exposure. The SMM degrade due to photoreduction with increasing time of exposure. The trivalent metallic components (here Mn and Cr) become divalent ones. This degradation process was observed by using very small photon fluxes at Maxlab III. Within about one hour of X-Ray exposure the degradation saturates. The rate of degradation depends on the substrate material as well as on the SMM-concentration on the substrate. Beneath these results we will present first spin-resolved photo-emission measurements of SMM-crystals.