1. Key Laboratory of Soft Chemistry
and Functional Materials (Ministry of Education) and Department of
Applied Physics, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, P. R. China
2. Department of Chemistry - Ångström
Laboratory, Uppsala Universitet, Box 538
SE-751 21, Uppsala, Sweden
3. Key Laboratory of Computational
Physical Sciences (Ministry of Education), State Key Laboratory of
Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, P. R. China