1. School of Chemistry, University of Birmingham, Edgbaston Campus, Birmingham B15 2TT, U.K.
2. Physics Department, Lancaster University, Lancaster LA1 4YB, U.K.
3. Department of Physics, College of Science, University of Anbar, Ramadi 31001, Anbar, Iraq
4. Department of Chemistry, Imperial College London, MSRH, White City, London W12 0BZ, U.K.
5. Physics Department, College of Science, University of Bisha, P.O. Box 344, Bisha 61922, Kingdom of Saudi Arabia
6. School of Information Science and Technology, Dalian Maritime University, Dalian 116026, China