SKM 2023 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 19: Molecular Magnetism I
MA 19.4: Vortrag
Dienstag, 28. März 2023, 15:45–16:00, HSZ 04
Spin transition of spin-crossover molecules supported by tridentate ligands deposited on HOPG — •Jorge Torres1, Jan Grunwald2, Sascha Ossinger2, Sangeeta Thakur1, Clara W. A. Trommer2, Marcel Walter1, Ivar Kumberg1, Rahil Hosseinifar1, Evangelos Golias1, Sebastien Hadjaj1, Jendrik Gördes1, Pin-Chi Liu1, Chen Luo3, Lalminthang Kipgen1, Tauquir Shinwari1, Florin Radu3, Felix Tuczek2, and Wolfgang Kuch1 — 1Freie Universität Berlin, Institut für Experimentalphysik, Berlin, Germany — 2Christian-Albrechts-Universität zu Kiel, Institut für Anorganische Chemie, Kiel, Germany — 3Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany
In a spin-crossover molecule (SCM) the excitation and relaxation processes can be stimulated by temperature, pressure or light. The latter is known as the light-induced excited spin-state trapping (LIESST) effect. The excitation of the high-spin (HS) and relaxation to low-spin (LS) state can exhibit single- or multi-exponential behavior. Here, we investigate the behavior of different thicknesses of the SCM [Fe{H2B(pz)(pypz)}2] [1] and [Fe{pypypyr}2] deposited on highly oriented pyrolytic graphite (HOPG) by X-ray absorption and differential reflectance spectroscopy. The results show that the amount of molecules in the HS state as a function of temperature at constant illumination presents a sigmoidal behavior. The relaxation rates are discussed in the context of the inverse energy gap law, which is usually invoked to interpret the LIESST behaviour of Fe(II) complexes.
[1] S. Ossinger et al., Inorg. Chem., 2020, 59, 7966-7979