Affiliation: | a Laboratoire de Physique Appliquée, Faculté des Sciences de Sfax, B. P. 1171, 3000 Sfax, Tunisia b Physics Department, Rabigh College of Science and Art, King Abdulaziz University, P.O. Box 344, Rabigh 21911, Saudi Arabia c Physics Department (I3N), Aveiro University, Campus Universitá rio de Santiago, 3800-193 Aveiro, Portugal |