1. Dipartimento
di Chimica “Giacomo Ciamician” dell’Università degli Studi di Bologna, via Selmi 2, I-40126 Bologna, Italy
2. INAF − Osservatorio di Radioastronomia (formerly Institute of Radioastronomy), via P. Gobetti, 101, I-40129 Bologna, Italy
3. Department
of Physics, Stockholm University, Albanova University Center, SE-106 91 Stockholm, Sweden