1. Department of Physics, Chaudhary Devi Lal University, Sirsa-125055, Haryana, India
2. Department of Physics, Pt.N.R.S.G.C.Rohtak, Maharshi Dayanand University, Rohtak-124001, Haryana, India (On Leave)
3. Department of Physics, Swami Shradhanand College, University of Delhi, Delhi, Delhi-110036, India