1. School of Instrumentation Science and Engineering Harbin Institute of Technology Harbin 150080 P. R. China
2. School of Chemistry and Chemical Engineering Harbin Institute of Technology Harbin 150080 P. R. China
3. Department of Physics School of Science Harbin University of Science and Technology Harbin 150080 China
4. School of Chemical and Environmental Engineering Harbin University of Science and Technology Harbin 150040 China
5. Department of Mathematics and Materials Research Institute The Pennsylvania State University Pennsylvania PA 16802 USA