1. Department of Chemistry, National Taiwan Univeristy, Taipei 106, Taiwan
2. Department of Chemistry, Stony Brook University, 100 Nicolls Road, Stony Brook, New York 11794-3400, USA
3. Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
4. Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 106, Taiwan