1. National Institute for Laser, Plasma and Radiation Physics, 077125 Magurele, Ilfov, Romania
2. Faculty of Chemistry, University of Bucharest, 050663 Bucharest, Romania
3. Institute of Biochemistry of the Romanian Academy, 060031 Bucharest, Romania
4. National Institute of Materials Physics, 077125 Magurele, Ilfov, Romania
5. Faculty of Physics, University of Bucharest, 077125 Magurele, Ilfov, Romania