1. Department of Physics, A.V.V.M Sri Pushpam College, Thanjavur 613 503, India
2. Department of Physics, Arignar Anna Govt Arts college Cheyyar 604 407, India
3. Department of Physics, D.G.Vaishnav College, Chennai 600 106, India
4. Department of Physics, Kandaswami College for Men, Anna Nagar East, Chennai , India