[1] Inst Ciencia Mat Barcelona CSIC ICMAB, Consejo Super Invest Cient, Bellaterra 08193, Spain
[2] Natl Inst Lasers Plasma & Radiat Phys, Bucharest 77125, Romania
[3] Natl Inst Mat Phys, Bucharest 77125, Romania
[4] Transilvania Univ Brasov, Brasov 500036, Romania