1. Department
of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, I-44123 Ferrara, Italy
2. Department
of Chemistry and Pharmaceutical Sciences, University of Ferrara, Via L. Borsari 46, I-44121 Ferrara, Italy
3. Research
Center for Non-Conventional Energy, Istituto Eni Donegani Environmental Technologies, via Maritano 26, San Donato
Milanese, Milan I-20097, Italy