Berlin 2008 – scientific programme
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MA: Fachverband Magnetismus
MA 29: Spin Structures / Magnetic Phase Transitions
MA 29.1: Talk
Thursday, February 28, 2008, 17:45–18:00, H 1012
XAFS investigation of the light and thermally induced low-spin to high-spin transition in metallo-supramolecular assemblies — •Bahia Arezki1, Yves Bodenthin2, Ronald Frahm3, Ralph Wagner3, Dirk Lützenkirchen-Hechta3, and Ullrich Pietsch1 — 1Fachbereich 7- Physik- Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen, Germany — 2) Paul Scherrer Institut, CH-5232 Villigen, Switzerland — 3Fachbereich C - Physik, Bergische Universität Wuppertal, Gaußstr. 20, 42097 Wuppertal, Germany
We have investigated the structural changes associated with the low spin to high spin transition (ST) of Metallo-supramolecular polyelectrolyte-amphiphile-complexes (PAC) induced by temperature and light. For this purpose, X-ray absorption near the edge (XANES)has been used to probe the structural changes in the local FeN6 octahedra, before and after a temperature induced ST. The PACs contain 2 (PAC6E16_12) and 6 (PAC6E16_16) amphiphiles per metal ion and are composed by Fe and Ni ions in order to identify any structural changes solely induced by the magnetic process. Our results clearly show changes in the profiles of both spin states indicating a structural modification during the ST. In next experiment, we will investigate if the same structural changes can be induced by light (LIESST-Light-Induced-Excited-Spin-State-Trapping). In case of success, this experiment, will be the first proof of LIESST in a metallo-polyelectrolyte embedded into an amphiphilic matrix. It will answer the question how the coordination shell of the Fe2+ ions looks after light irradiation.