1. The
Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
2. Department
of Chemistry, Iowa State University, Ames, Iowa 50011, United States
3. GWC Technologies Inc., Madison, Wisconsin 53719, United States
4. Department
of Materials Science and Engineering, Iowa State University, Ames, Iowa 50011, United States
5. Department
of Physics, Mansoura University, Mansoura, 35516, Egypt
6. Department
of Electrical and Computer Engineering, Iowa State University, Ames, Iowa 50011, United States