1. Energy Technology
Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan
2. Department of Applied Chemistry, Chuo University, Kasuga 1-13-27, Bunkyo-ku, Tokyo 112-8551,
Japan
3. The Institute for Solid
State
Physics, The University of Tokyo, Kashiwa,
Chiba 277-8581, Japan