1. Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati 781039, India
2. Saha Institute of Nuclear Physics, HBNI, 1/AF Bidhannagar, Kolkata 700064, India
3. School of Physical Sciences, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032, India
4. Kadihati KNM High School, Ganti, Kolkata 700132, India
5. Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, India