1. Department of Physics, Velammal College of Engineering & Technology, Madurai, Tamil Nadu, India
2. Department of Physics, National Institute of Technology, Tiruchirapalli, Tamil Nadu, India
3. Department of Physics, Karpagam Academy of Higher Education, Coimbatore, Tamil Nadu, India
4. Department of Physics, B.S. Abdur Rahman Crescent Institute of Science & Technology, Vandalur, Chennai, Tamil Nadu, India