1. Department of Physics, Kathmandu University, Dhulikhel, Kavre, Nepal
2. Department of Physics, Tri-Chandra Multiple Campus, Tribhuvan University, Ghantaghar, Kathmandu, Nepal
3. Department of Environmental Science and Engineering, Kathmandu University, Dhulikhel, Kavre, Nepal
4. Department of Chemical Science and Engineering, Kathmandu University, Dhulikhel, Kavre, Nepal