1. Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-Ku, Kyoto 615-8510, Japan
2. Institute for Quantum Life Science, National Institutes for Quantum and Radiological Science and Technology, 4-9-1, Anagawa, Inage-Ku, Chiba 263-8555, Japan
3. Laboratory for Solid State Physics, Eidgenössische Technische Hochschule (ETH) Zürich, CH-8093 Zürich, Switzerland
4. Department of Physics, Ben-Gurion University of the Negev, 8410501 Beer-Sheva, Israel
5. Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, 1233 Watanuki, Takasaki, Gunma 370-1292, Japan
6. NanoCarbon Research Institute, AREC, Shinshu University, Ueda, Nagano 386-8567, Japan