1. Department of Physics, Cooch Behar Panchanan Barma University, Cooch Behar, India
2. Department of Chemistry, Cooch Behar Panchanan Barma University, Cooch Behar, India
3. Department of Nanotechnology, North-Eastern Hill University, Shillong, India
4. Department of Physics, Dinhata College, Dinhata, India