1. School of Physics and Electronics, Institute of Materials and Clean Energy Shandong Normal University Jinan 250014 China
2. College of Chemistry, Chemical Engineering and Materials Science, Institute of Biomedical Sciences Shandong Normal University Jinan 250014 China
3. Department of Physics and Astronomy University of Kansas Lawrence Kansas 66045 USA
4. Shandong Provincial Hospital Shandong First Medical University Jinan 250021 China