Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy

CPP 22.14: Poster

Mittwoch, 28. März 2007, 16:00–18:30, Poster B

Single-laser-pulse-induced switching of molecular spin states — •Sébastien Bonhommeau¹, Niko Pontius¹, Hermann Dürr¹, Wolfgang Eberhardt¹, Saioa Cobo², Gabor molnár², and Azzedine Bousseksou² — ¹Berliner Elektronenspeicherring-Gesellshaft für Synchrotronstrahlung m.b.H (BESSY), Albert-Einstein-Straße 15, 12489 Berlin, Germany — ²Laboratoire de Chimie de Coordination, CNRS UPR-8241, Route de Narbonne 205, 31077 Toulouse, France

Light-induced phenomena in spin crossover complexes have aroused a lot of interest since the discovery of the LIESST (Light-Induced Excited Spin State Trapping) effect in solid state. Here, we demonstrate by means of Raman spectroscopy that a bi-directional spin transition can be obtained at room temperature when applying a nanosecond laser pulse in the hysteresis loop of the spin crossover complex Fe(pyrazine)[Pt(CN)₄]. This phenomenon is interpreted as a photo-induced phase transition exhibiting a threshold energy density. In order to provide a deeper insight on the electronic properties of such polymeric materials, X-ray photoemission and absorption experiments have also been performed on a multilayer assembly of thin films of Fe(azopyridine)[Pt(CN)₄] that display spin crossover. This information is of paramount importance to shed new light on the photo-induced dynamics, in the subpicosecond time scale, which will be investigated using the femtoslicing facility now available at BESSY GmbH.