1. Carbon Nanotechnology Laboratory, Department of Physics and Centre of Excellence in Advanced Materials; National Institute of Technology; Durgapur 713209 West Bengal India
2. School of Physics; University of Hyderabad; 500046 India
3. CSIR-Central Mechanical Engineering Research Institute; Durgapur 713209 West Bengal India
4. Department of Physics; University of Liverpool; L69 7ZE United Kingdom