1. Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education School of Chemistry and Materials ScienceHeilongjiang University Harbin 150080 P. R. China
2. Department of Physics and Engineering PhysicsThe University of Tulsa Tulsa OK 74104 USA
3. Department of ChemistryTsinghua University Beijing 100084 P. R. China
4. State Key Laboratory on Integrated Optoelectronics College of Electronic Science and EngineeringJilin University Changchun 130012 P. R. China