1. Department of Chemistry National Tsing Hua University No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 30013 Taiwan
2. Institute of Atomic and Molecular Sciences Academia Sinica Taipei 10617 Taiwan
3. Department of Physics National Taiwan Normal University Taipei 11677 Taiwan
4. Department of Chemistry National Taiwan University Taipei 106 Taiwan
5. Physics Division National Center for Theoretical Sciences Taipei 106 Taiwan
6. College of Semiconductor Research National Tsing Hua University No. 101, Sec. 2, Kuang-Fu Rd. Hsinchu 30013 Taiwan