1. Institute for Laser Technology, Utsubo-Hommachi 1-8-4 Nishi-ku, Osaka 550, Japan Department of Biophysics, Graduate School of Science Kyoto University, Sakyo-ku, Kyoto 601-01, Japan Department of Physics, Graduate School of Science Nagoya University, Furo-cho Chikusa-ku, Nagoya 464-01, Japan