1. Department of Physics, Indiana State University, Terre Haute, Indiana 47809, USA
2. Office of Information Technology, Indiana State University, Terre Haute, Indiana 47809, USA
3. Office of the Chancellor and Department of Chemistry & Biochemistry and Department of Physics & Astronomy, University of Missouri—St. Louis, St. Louis, Missouri 63121, USA
4. School of Physics, Nanjing University, Nanjing 210093, China