1. Department of Physics and Earth Sciences, University of Ferrara, Via Giuseppe Saragat 1/C, 44122 Ferrara, Italy
2. CNR-ICCOM, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy
3. CSGI, Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy
4. Sensors and Devices Center, Bruno Kessler Foundation, Via Sommarive 18, 38123 Trento, Italy
5. CNR-IFAC, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Italy