1. Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2−1 Yamada-oka, Suita, Osaka 565−0871, Japan
2. Division of Organic Chemistry and Biochemistry, Rudjer Bošković Institute, Bijenička c. 54, HR−10000 Zagreb, Croatia
3. ESR Division, Bruker Biospin K.K., 3−9 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa 221-0022, Japan