1. State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 0300006, China
2. Nanocluster Laboratory, Institute of Molecular Science, Shanxi University, Taiyuan 030006, China
3. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
4. Institut für Chemie und Biochemie, Freie Universiät Berlin, 14195 Berlin, Germany