1. Department
of Physics, National Central University, Jhongli 32001, Taiwan
2. Neutron
Group, National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
3. Department
of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
4. Department
of Physics and National High Magnetic Field Laboratory, University of Florida, Gainesville, Florida 32611-8440, United States