1. Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi, 15310 Athens, Greece
2. Department of Chemistry, Laboratory of Bioinorganic Chemistry, University of Crete, Voutes Campus, Heraklion 70013 Crete, Greece
3. Solid State Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Zografos, Athens, Greece
4. Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Vas. Constantinou Avenue 48, 11635 Athens, Greece