1. Shanghai Key Lab of Modern Optical System, Ministry of Education, University of Shanghai for Science and Technology, Shanghai 200093, China
2. Department of Environmental Engineering, Technical University of Denmark (DTU), 2800 Kgs, Lyngby, Denmark
3. State Key Laboratory Breeding Base of Coal Science and Technology Co-founded by Shanxi Province and the Ministry of Science and Technology, Taiyuan University of Technology, Taiyuan 030024, China