1. Department of Chemistry Jagannath University Dhaka 1100 Bangladesh 9583794
2. Center of Research Excellence in Nanotechnology King Fahd University of Petroleum & Minerals, KFUPM Box 5040 Dhahran 31261 Saudi Arabia
3. Physics Department King Fahd University of Petroleum & Minerals, KFUPM Box 5047 Dhahran 31261 Saudi Arabia