1. 1Department of Physics, Government Arts College, Salem-636007, India 2Department of Physics, Arignar Anna Government Arts College, Villupuram-605602, India
2. Department of Physics, Government Arts College for Men (Autonomous), Nandanam, Chennai-600035, India
3. Department of Physics, St. Joseph’s College (Arts & Science) Kovur, Chennai-600128, India
4. Department of Physics, Government Arts College, Salem-636007, India