1. Synchrotron Radiation Research Center, No.7 1 R&D Road VI, Hsinchu 300, Taiwan, R.O.C
2. Center for Condensed Matter Sciences, National Taiwan University, Taipei 106, Taiwan, R.O.C
3. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C
4. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan, R.O.C
5. Department of Physics, National Tsing-Hua University, Hsinchu 300, Taiwan, R.O.C
6. Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, D-69120 Heidelberg, Germany
7. Department of Biomedical Engineering, Chung Yuan Christian University, Chung-Li, Taoyuan 32023, Taiwan, R.O.C