1. Department of Physics, Fatima College, Madurai 625 018, India
2. Department of Physics, Government Arts College, Melur 625 106, Madurai, India
3. Department of Chemical Engineering, College of Engineering, Kyung Hee University, 1732 Deogyeong-daero, Giheung, Yongin, Gyeonggi 446-701, Republic of Korea