1. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029, P. R. China
2. School of Chemical Engineering, Dalian University of Technology, Dalian, Liaoning 116024, P. R. China
3. State Key Laboratory of Fire Science, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China