1. Center of Excellence for Nanostructured Materials (CENMAT), Dipartimento di Scienze Farmaceutiche and Italian Interuniversity Consortium on Materials Science and Technology, Unit of Trieste, Università degli Studi di Trieste, Piazzale Europa 1, 34127 Trieste, Italy, Institute of Chemical Engineering and High Temperature Chemical Processes, Foundation for Research and Technology−Hellas, P.O. Box 1414, 26504 Patras, Greece, and Department of Physics, University of Patras, 26504 Patras, Greece