1. Institute of Nanoscience and Nanotechnology; National Center for Scientific Research Demokritos; 15310 Agia Paraskevi Attiki Greece
2. Department of Physics; University of Patras; 26504 Patras Greece
3. Section of Solid State Physics; Physics Department; University of Athens; Panepistimioupolis 15784 Zografos Athens Greece
4. Department of Natural Sciences; University of Chester; Thornton Science Park CH2 4NU Chester UK
5. Materials Research Institute; School of Engineering and Materials Science; Queen Mary University of London; London E1 4NS UK
6. Department of Chemical Engineering; University of Patras; 26504 Patras Greece