1. State Key Laboratory of Integrated Optoelectronics and College of Electronic Science and EngineeringJilin University Changchun 130012 China
2. Department of Chemistry and PhysicsLouisiana State University Shreveport LA 71115 USA
3. Department of ChemistryBrown University Providence RI 02912 USA
4. Key Laboratory of Materials Physics of Ministry of EducationDepartment of Physics and EngineeringZhengzhou University Zhengzhou 450052 China