[1] Department of Physics, Kathmandu University, Kavre, Dhulikhel, Nepal
[2] Department of Physics, Tri-Chandra Multiple Campus, Tribhuvan University, Ghantaghar, Kathmandu, Nepal
[3] Department of Environmental Science and Engineering, Kathmandu University, Kavre, Dhulikhel, Nepal
[4] Department of Chemical Science and Engineering, Kathmandu University, Kavre, Dhulikhel, Nepal
[5] Department of Electronics and Communication, Nepal Engineering College, Pokhara University, Bhaktapur, Changunarayan, Nepal