1. Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) Technische Universität Dresden 01069 Dresden Germany
2. Physics Department Durham University Durham DH1 3LE UK
3. Key Laboratory of Green Chemistry and Technology (Ministry of Education) College of Chemistry Sichuan University Chengdu 610064 P. R. China
4. School of Materials Science and Engineering Qilu University of Technology (Shandong Academy of Sciences) Jinan 250353 P. R. China
5. Analytical & Testing Centre Sichuan University Chengdu 610064 P. R. China
6. Department of Chemistry Duke University Durham NC 27708 USA