1. State Key Laboratory of Loess and Quaternary Geology (SKLLQG), Key Laboratory of Aerosol Chemistry and Physics, Institute of Earth Environment, Chinese Academy of Sciences , Xi’an 710061 , China
2. Center of Excellence in Quaternary Science and Global Change, Chinese Academy of Sciences , Xi’an 710061 , China
3. University of Chinese Academy of Sciences , Beijing 100049 , China
4. Hefei National Research Center for Physical Sciences at the Microscale, School of Chemistry and Materials Science, and National Synchrotron Radiation Laboratory, University of Science and Technology of China , Hefei 230026 , China
5. Institute of Atmospheric Physics, Chinese Academy of Sciences , Beijing 100190 , China
6. School of Physics and Information Technology, Shaanxi Normal University , Xi’an 710062 , China