1. Department of Electricity, Solid-State Physics and Biophysics, Faculty of Physics, University of Bucharest, 405 Atomistilor Street, 077125 Magurele, Romania
2. CTT-3Nano-SAE Research Center, Faculty of Physics, ICUB, University of Bucharest, MG-38, 405 Atomistilor Street, 077125 Magurele, Romania
3. National Institute for Chemical-Pharmaceutical Research and Development, 112 Vitan Avenue, 031299 Bucharest, Romania
4. National Institute for Lasers, Plasma and Radiation Physics, Magurele, 077125 Bucharest, Romania
5. Academy of Romanian Scientists, Ilfov Street 3, 050045 Bucharest, Romania