1. 1Department of Physics, Bharathiyar University, Coimbatore (Tamil Nadu) India.
2. 2Department of Physics, Chikkaiah Naicker College, Erode (Affiliated to Bharathiyar University, Tamil Nadu) India.
3. 3Department of Physics, Vivekanandha College of Engineering for Women (Autonomous), (Affiliated to Anna University, Chennai), Elayampalayam, Tiruchengode, (Tamil Nadu) India.
4. 4Khadir Mohideen College (Affiliated to Bharathidasan University, Thiruchirappalli), Adirampattinam, Thanjavur, Tamil Nadu, India.