1. Center for Atomic, Molecular Physics and Quantum Optics (CEPAMOQ), University of Douala, Douala, Cameroon
2. Faculty of Medicine and Health Sciences, University of Sherbrooke, Sherbrooke, Canada
3. Department of Physics, Faculty of Science, University of Lomé, Lomé, Togo
4. Faculty of Sciences, University of Douala, Douala, Cameroon
5. Department of Subatomic Physics, NRF/iThemba LABS, Somerset West, South Africa
6. Laboratory of Material Sciences, Environment and Solar Energy (LASMES) of University Felix Houphouët Boigny, Abidjan, Côte d’Ivoire
7. Faculty of Exact and Applied Sciences, Department of Physics, Laboratory of Renewable Energies and Materials, University of N’Djamena, N’Djamena, Chad