1. Solid
State Physics Section, Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
2. Department
of Chemistry, University of Wisconsin − Whitewater, Whitewater, Wisconsin 53190, United States
3. Department
of Chemistry, Northwestern University, Evanston, Illinois 60208, United States
4. Materials
Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States