Affiliation: | 1. Department of Physics, Korea University, Seoul 136‐713 (South Korea), Fax: (+82)?2‐927‐3292;2. Department of Chemistry, Korea University, Seoul 136‐713 (South Korea), Fax: (+82)?2‐925‐4284;3. Department of Physics, University of Incheon, Incheon 406‐772 (South Korea) |