1. Molecular and Biomolecular Physics Department; National Institute for R&D of Isotopic and Molecular Technologies; Donat Street, No 67-103 RO-400293 Cluj-Napoca Romania
2. Istituto Motori-National Research Council of Italy; Via Marconi 4 80125 Napoli Italy
3. Correspondence to: Istituto Motori-CNR; Via Marconi 8 80125 Napoli Italy