1. Key Laboratory of Nanobiosensing and Nanobioanalysis at Universities of Jilin Province, Faculty of Chemistry, Northeast Normal University, Renmin Street No. 5268, Changchun 130024, China
2. State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, P. R. China
3. College of Physics, Changchun Normal University, Changchun 130032, China
4. Department of Chemistry, Durham University, Durham DH1 3LE, U.K.