1. Institute of Nanoscience and Nanotechnology (INN), National Center for Scientific Research (NCSR) “Demokritos”, 15341 Agia Paraskevi, Attica Greece
2. Department of Physics, University of Konstanz, 78457 Konstanz, Germany
3. Department of Physics, University of Patras, 26504 Patras, Greece
4. Department of Chemical Engineering, University of Patras, 26504 Patras, Greece
5. Department of Chemistry, Quaid-i-Azam University, Islamabad 45320, Pakistan
6. Solid State Physics Section, Physics Department, National and Kapodistrian University of Athens, Panepistimioupolis, 15784 Zografos, Athens Greece
7. Faculty of Engineering, Environment and Computing, Coventry University, Priory Street, Coventry CV1 5FB, United Kingdom