1. Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009, India
2. Soft Condensed Matter Laboratory, Raman Research Institute, Bangalore 560080, India
3. Department of Chemistry, University of Science & Technology Meghalaya, Ri-Bhoi, Meghalaya 793101, India
4. Department of Chemistry, Assam University, Silchar, Assam-788011, India