1. Department of Chemical Engineering and Frontier Research Center on Fundamental and Applied Sciences of Matters, National Tsing Hua University, Hsinchu 30013, Taiwan
2. National Synchrotron Radiation Research Center, Hsinchu 300, Taiwan
3. Quantum Beam Science Center, Japan Atomic Energy Agency, Tokai-mura, Naka-gun, Ibaraki 319-1195, Japan and Kyoto University, Kyoto 606-6501, Japan
4. Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu 300, Taiwan