1. Sensor Lab Department of Information Engineering University of Brescia and UdR INSTM of Brescia Via Valotti 9 Brescia 25133 Italy
2. Department of Engineering “Enzo Ferrari” University of Modena and Reggio Emilia Via Vivarelli 10 Modena 41125 Italy
3. Department of Physics South–Ukrainian University Staroportofrankovskaya str. 26 Odessa 65020 Ukraine
4. Chemistry and Advanced Materials Group Faculty of Engineering and Natural Sciences Tampere University Korkeakoulunkatu 8, P.O. Box 541 Tampere FI‐33014 Finland
5. Physics Department University of Rome ‘La Sapienza' P.le A. Moro 5 Rome 00185 Italy
6. INFN‐LNF Via E. Fermi 40 Frascati 00044 Italy
7. ISMN – CNR PO Box 10, 00015 Monterotondo Stazione Rome Italy