1. School of Materials Science and EngineeringKunming University of Science and Technology Kunming 650093 P. R. China
2. Research Center for Analysis and MeasurementKunming University of Science and Technology Kunming 650093 P. R. China
3. Analysis and Test Center of Yunnan Province Kunming 650093 P. R. China
4. Faculty of Chemical EngineeringKunming University of Science and Technology Kunming 650093 P. R. China
5. Institute of Theoretical ChemistryJilin University Changchun 130023 P. R. China