1. Institute
of Chemistry, Academia Sinica, Taipei 115, Taiwan
2. Department
of Engineering and System Science, National Tsing Hua University, Hsinchu 300, Taiwan
3. Nano
Science and Technology Program, Taiwan International Graduate Program, Academia Sinica, Taipei 115, Taiwan, and National Tsing Hua University, Hsinchu 300, Taiwan
4. Department
of Physics, National Taiwan University, Taipei 106, Taiwan
5. Department
of Chemical Engineering, National Taipei University of Technology, Taipei 106, Taiwan
6. Institute
of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan
7. Center
for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan