1. Department of Physics and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul 121-742, Korea, Department of Physics, University of California, Berkeley, California 94720, Ames Laboratory and Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, and Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan