1. Department of Physical and Chemical Sciences, University of L’Aquila, Via Vetoio, 67100 L’Aquila, Italy
2. Department of Environmental Engineering, University of Calabria, 87036 Rende, Italy
3. Department of Physics, University of Calabria, 87036 Rende, Italy
4. Institute of Nanotechnology (Nanotec)—UoS Cosenza, National Research Council, 87036 Rende, Italy
5. CNISM—National Interuniversity Consortium for the Physical Sciences of Matter, Via della Vasca Navale 84, 00146 Roma, Italy