1. Laboratoire de Physique Appliquée, Faculté des Sciences, Université de Sfax, Tunisia
2. University of Coimbra, CQC-IMS, Department of Chemistry, 3004-535 Coimbra, Portugal
3. University of Coimbra, CFisUC, Physics Department, 3004-516 Coimbra, Portugal
4. Departamento de Física Aplicada, Facultade de Óptica e Optometría, Campus Vida, Universidade de Santiago de Compostela (USC), 15782 Galicia, Spain