Kroll T, Aristov V Yu, Molodtsova O V, Ossipyan Yu A, Vyalikh D V, Büchner B, Knupfer M
IFW Dresden, P.O. Box 270016, D-01171 Dresden, Germany.
J Phys Chem A. 2009 Aug 6;113(31):8917-22. doi: 10.1021/jp903001v.
The 3d orbital ground state of transition-metal ions that are incorporated in a molecular matrix determines the total spin of the transition-metal ion as well as the spin anisotropy and thus the essential magnetic properties of the corresponding molecule. However, there is little known to date on the exact 3d ground state of many molecular systems, including quite complex molecular magnets as well as relatively simple systems such as, for instance, cobalt phthalocyanine (CoPc). For the latter, there are contradictory theoretical predictions with respect to the occupation of the various Co 3d electronic levels. We demonstrate that polarization-dependent X-ray absorption spectroscopy in combination with a simulation of the spectra is able to shed a brighter light on the spin and orbital ground state of the transition-metal ion in CoPc. Our results reveal a temperature-dependent ground state and emphasize the importance of taking 3d correlation effects properly into account.
掺入分子基质中的过渡金属离子的3d轨道基态决定了过渡金属离子的总自旋以及自旋各向异性，进而决定了相应分子的基本磁性能。然而，迄今为止，对于许多分子体系的精确3d基态，包括相当复杂的分子磁体以及相对简单的体系，如钴酞菁（CoPc），人们了解甚少。对于后者，关于各种Co 3d电子能级的占据情况存在相互矛盾的理论预测。我们证明，偏振相关X射线吸收光谱与光谱模拟相结合，能够更清楚地揭示CoPc中过渡金属离子的自旋和轨道基态。我们的结果揭示了一种与温度相关的基态，并强调了正确考虑3d相关效应的重要性。
