1. Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, United States
2. Department of Physics, Technical University of Denmark, DTU Risø Campus,
Frederiksborgvej 399, Building 108-121-129-228, DK-4000 Roskilde,
Denmark
3. Max Planck Institute for Chemical Physics of Solids, Nöthnitzer
Strasse 40, D-01187 Dresden, Germany
4. Quantum Condensed Matter Division, Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831,
United States
5. Helmholtz Zentrum Berlin for Materials and Energy,
Kekuléstrasse 5, D-14109 Berlin, Germany
6. Materials Research Division, Technical University of Denmark, AFM-228, Frederiksborgvej 399,
P.O. Box 49, DK-4000 Roskilde, Denmark
7. Laboratory for Electron Microscopy, Karlsruhe Institute of Technology, Engesserstrasse
7, Geb. 30.22 (Physik Flachbau), 2. OG, Zimmer 228, D-76128 Karlsruhe,
Germany