1. Department of Physics, The University of Dodoma, Tanzania
2. Department of Physics, Geethanjali College of Engineering & Technology, Keesara, RR Dist., 501 301, TS., India
3. Department of Physics, Acharya Nagarjuna University, Nagarjuna Nagar, Guntur, 522 510, AP., India
4. Department of Physics, Osmania University, Hyderabad, 500007,TS., India