1. Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
2. Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 106, Taiwan
3. Department of Applied Chemistry, National Chiao Tung University, Hsinchu 30010, Taiwan
4. Institute of Atomic and Molecular Sciences, Academia Sinica, P.O. Box 23-166, Taipei 106, Taiwan