1. Max-Planck-Institut für Chemische Physik fester Stoffe, Nöthnitzer Strasse 40, 01187 Dresden, Germany
2. Department of Chemistry and the Texas Center for Superconductivity, University of Houston, Houston, Texas 77204-5003, United States
3. Institute of Structure Physics, Triebenberg Laboratory for High-Resolution Electron Microscopy and Holography, Technical University of Dresden, Zum Triebenberg 50, 01328 Dresden Zaschendorf, Germany