1. National Institute for Materials Physics, P.O. Box MG 07, Magurele, 077125 Bucharest, Romania
2. Faculty of Physics, University of Bucharest, 405 Atomistilor Street, P.O. Box MG1, 077125 Magurele, Romania
3. National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor Street, P.O. Box MG 36, Magurele, 077125 Bucharest, Romania
4. Horiba Jobin Yvon S.A., 16-18 rue du Canal, 91165 Longjumeau Cedex, France
5. S.C. METAV R&D S.A., 020011 Bucharest, Romania