1. Department
of Organic and Polymeric Materials, Graduate School of Science and
Engineering, Tokyo Institute of Technology, 2-12-1-I6-31 Ookayama, Tokyo 152-8552, Japan
2. National
Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China
3. Condensed
Matter Science Unit, Quantum Beam Science Center, Japan Atomic Energy Agency (JAEA), 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
4. National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan
5. Research
Center for Simulation Science, Japan Advanced Institute of Science and Technology (JAIST), 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan