[1] Adekunle Ajasin Univ, Phys & Elect Dept, Akungba Akoko 342111, Ondo State, Nigeria
[2] Univ Benin, Dept Phys, Benin, Edo State, Nigeria
[3] Prince Sattam Bin Abdulaziz Univ, Coll Sci & Humanities Al Kharj, Phys Dept, Al Kharj 11942, Saudi Arabia
[4] King Fahd Univ Petr & Minerals, Chem Dept, Dhahran 31261, Saudi Arabia