1. Key Laboratory of Environmental Optics and Technology and Environmental Materials and Pollution Control Laboratory, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China
2. Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
3. Shanghai Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201204, China