1. National Laboratory for Molecular Sciences, State Key
Laboratory of Rare Earth Materials Chemistry and Applications, College
of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China
2. Institut für Physikalische Chemie, Universität Stuttgart, Pfaffenwaldring 55, Stuttgart D-70569, Germany
3. Institut Néel−CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9, France