1. Department of Engineering Physics, Polytechnique Montreal, C.P. 6079, Succ. Centre-ville, Montréal, Québec H3C 3A7, Canada
2. Department of Electronic, Electrical and Information Engineering (DEI), University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy
3. Département de chimie, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec H3C 3J7, Canada
4. Department of Physics “Ettore Pancini”, University of Naples “Federico II”, Complesso Universitario Monte S. Angelo, Via Cintia 1, 80126 Naples, Italy