1. Department of Radiation Physics, National Center for Radiation Research and Technology (NCRRT), Atomic Energy Authority (AEA), Nasr City, Cairo 11787, Egypt
2. Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA
3. Department of Physics, University of California, Santa Cruz, California 95064, USA
4. College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, China