1. Institute of Mathematic and Physical Sciences (IMSP), Dangbo, Benin
2. UNSTIM, ENS-Natitingou, Laboratory of Physics and Applications (LPA), Abomey, Benin
3. Department of Physics, University of Abomey-Calavi, Calavi, Benin
4. Department of Physics, Erciyes University, Kayseri, Turkey