1. R&D Headquarters Canon Research Center, Canon Inc., 5-1 Morinosato-Wakamiya, Atsugi-shi, Kanagawa 243-0193, Japan, Department of Applied Chemistry, Waseda University, Ohkubo-3, Shinjuku-ku, Tokyo 169-8555, Japan, and Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, Nishiwaseda-2, Shinjuku-ku, Tokyo 169-0051, Japan