1. Institute of Nanoscience and Nanotechnology, National Center for Scientific Research Demokritos, Agia Paraskevi, 15310 Athens, Greece
2. Department of Chemistry, University of Crete, Laboratory of Bioinorganic Chemistry, Voutes Campus, Heraklion 70013, Crete, Greece
3. Solid State Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Zografos, Athens, Greece