1. National Synchrotron Radiation Research Center, No. 101, Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan
2. Escuela
de Quimica, Universidad de Costa Rica, Ciudad Universitaria Rodrigo Facio, San
Pedro de Montes de Oca, San Jose 11501-2060, Costa Rica
3. Department
of Mathematics, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada V5A1S6