Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 44: Poster Session II (Semiconductors; Oxides and Insulators: Adsorption, Clean Surfaces, Epitaxy and Growth; Surface Chemical Reactions and Heterogeneous Catalysis; Surface or Interface Magnetism; Solid-Liquid Interfaces; Organic, Polymeric, Biomolecular Films; Particles and Clusters; Methods: Atomic and Electronic Structure; Time-resolved Spectroscopies)
O 44.24: Poster
Mittwoch, 28. März 2007, 17:00–19:30, Poster C
X-ray absorption of spin crossover complexes — •Matthias Bernien1, Marten Piantek1, Jorge Miguel1, Radu Abrudan1, Heiko Wende1,2, Wolfgang Kuch1, Marco Haryono3, Holger Kämpf3, and Andreas Grohmann3 — 1Freie Universität Berlin, Fachbereich Physik, Arnimalle 14, D-14195 Berlin, Germany — 2Universität Duisburg-Essen, Fachbereich Physik, Lotharstr. 1, D-47048 Duisburg, Germany — 3Technische Universität Berlin, Institut für Chemie, Straße des 17. Juni 135, D-10623 Berlin, Germany
Spin crossover (SCO) molecular complexes consist of a central metal ion surrounded by organic ligands. Depending on temperature, pressure, or optical excitation, these complexes can switch between two magnetic states, for which the electrons of the d-orbitals align such that their spins add up (high spin) or compensate partly (low spin) [1].
We report on X-ray absorption (XAS) measurements of thin layers of Fe(II) bispyrazolylpyridine SCO complexes deposited from solution on gold metal surfaces. By means of angle-dependent XAS at the C- and N-K edges we determine the alignment of the molecules on the surface, whereas their spin state is determined by comparing the Fe-L3,2 spectra to measurements on bulk samples. We find that the interaction with the surface plays an important role on the switching phenomenon.
[1] O. Kahn and C.J. Martinez, Science 279, 44 (1998)