1. Department
of Optoelectronic Engineering, National Dong Hwa University, Hualien 97401, Taiwan
2. Karlsruhe Institute of Technology (KIT), Institut
für Anorganische Chemie, Engesserstraße 15, Karlsruhe D-76131, Germany
3. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan