1. Department of Physics Guangxi Normal University Guilin China
2. Department of Materials Science and Engineering City University of Hong Kong Kowloon Hong Kong
3. Guangxi Key Laboratory of Low Carbon Energy Materials Guangxi Normal University Guilin China
4. Guangxi Key Laboratory of Nuclear Physics and Technology Guangxi Normal University Guilin China
5. State Key Laboratory for Chemistry and Molecular Engineering of Medicinal Resources Guangxi Normal University Guilin China