1. National Institute for Materials Physics, P.O. Box MG 07, 077125 Magurele, Romania
2. National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, P.O. Box MG 36, 077125 Magurele, Romania
3. Faculty of Physics, University of Bucharest, 405 Atomistilor Street, P.O. Box MG1, 077125 Magurele, Romania
4. Horiba Jobin Yvon SAS, 16-18 Rue du Canal, 91165 Longjumeau Cedex, France
5. Microbiology Department, Faculty of Biology, University of Bucharest, 1–3 Portocalelor Lane, Sector 5, 77206 Bucharest, Romania
6. Earth, Environmental and Life Sciences Section, Research Institute of the University of Bucharest, 1–3 Portocalelor Lane, Sector 5, 77206 Bucharest, Romania
7. Center for Microscopy-Microanalysis and Information Processing, University Politehnica of Bucharest, 313 Splaiul Independentei, 060042 Bucharest, Romania