1. Institute of Chemical Engineering Sciences, Foundation of Research and Technology Hellas, P.O. Box 1414, GR-26504 Patras, Greece
2. Department of Physics, University of Patras, GR-26504 Patras, Greece
3. P.N. Lebedev Physical Institute, Russian Academy of Sciences, 119991 Moscow, Russia
4. Department of Chemical Engineering, University of Patras, Patras 26504, Greece
5. School of Physics, Department of Solid-State Physics, Aristotle University of Thessaloniki, Thessaloniki 54124, Greece