Regensburg 2010 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 7: Electronic and Optical Properties of Organic Systems II
CPP 7.7: Vortrag
Montag, 22. März 2010, 15:30–15:45, H39
Visualizing the spin states of surface deposited Fe(II) spin-crossover compounds — •M. Stocker1, M. S. Alam1, A. Volkov1, U. Mitra1, K. Gieb1, M. Haryono2, K. Student2, A. Grohmann2, V. Dremov1, and P. Müller1 — 1Department of Physics and Interdisciplinary Center for Molecular Materials (ICMM), Universität Erlangen-Nürnberg, Germany. — 2Institut für Chemie, Technische Universität Berlin, Germany.
We present a novel method for determining the spin states of individual molecules and small clusters of surface deposited Fe(II) spin crossover (SCO) compounds by STM. Here we focus on [FeII(L)2](BF4)2 (L=2,6-di(1H-pyrazol-1-yl)-4-(thiocyanatomethyl)pyridine)1. For comparison, a high spin (HS) compound with a similar coordination motif was investigated. 10−8 molar solutions of the materials were drop-coated onto HOPG substrates and investigated by STM and CITS. A strong contrast between two distinct states of the SCO compound was found in the conductivity map, whereas the HS reference molecules always showed the same contrast. Therefore, the two different states can be identified with the high spin and low spin states. Switching of the spin state from high- to low-spin state and vice versa were observed at room temperature. Indications for a widening of the spin transition were found by varying the temperature.2
1 M. Haryono, et al., Eur. J. Inorg. Chem. 2009, 2136.
2 M.S. Alam, et al., Angew. Chem. (2009) (accepted).