1. Institute of Geosciences and Earth Resources, National Research Council, Via G. La Pira 4, 50121 Florence, Italy
2. Centro Fermi—Museo Storico della Fisica e Centro Studi e Ricerche “Enrico Fermi”, P.za del Viminale 1, 00184 Rome, Italy
3. Department of Physics
and Astronomy, University of Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
4. Department DICAM, University of Bologna, Via Terracini
28, 40131 Bologna, Italy
5. Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino (Florence), Italy