Department of Physics, Faculty of Sciences and Technologies, University of Kara, BP: 404, Kara, Togo,Department of Physics, Faculty of Sciences, University of Lome, BP: 1515, Lome, Togo
Department of Physics, Faculty of Sciences, University of Lome, BP: 1515, Lome, Togo
Department of Physics, University of Perpignan, Perpignan, France