1. CAS Key Laboratory of Standardization and Measurement for Nanotechnology
2. CAS Center of Excellence for Nanoscience
3. National Center for Nanoscience and Technology
4. Beijing 100190
5. P. R. China
6. National Institute of Advanced Industrial Science and Technology (AIST)
7. Tsukuba 305-8565
8. Japan
9. Petrochemical Research Institute
10. PetroChina
11. Beijing
12. P.R. China
13. Department of Applied Physics
14. Chongqing University
15. Chongqing 401331