1. Department of Chemistry and Chemical Engineering, Baoji University of Arts and Sciences, Baoji, 721013, P.R. China
2. School of Science, Xidian University, Xi'an 710071, P.R. China
3. Nonlinear Research Institute, Baoji University of Arts and Sciences, Baoji, 721016, P.R. China
4. Department of Physics, Northwest University, Xi'an 710069, P.R. China