1. Department of Physics , Tamilnadu College of Engineering , Coimbatore - 641 659 , Tamilnadu, India
2. Department of Physics, Coimbatore Institute of Technology , Coimbatore - 641 014 , Tamilnadu, India
3. Department of Physics, PPG Institute of Technology , Coimbatore - 641 035 , Tamilnadu, India
4. Department of Chemistry, Dr. N.G.P. Institute of Technology , Coimbatore - 641048 , Tamilnadu, India