1 Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan. t_fujimori@shinshu-u.ac.jp.
2 Institute of Carbon Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan.
3 Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan, 48824, USA.
4 Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1, Kamitomioka, Nagaoka, 940-2188, Japan.
5 Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan.
6 Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki-shi, Nagasaki, 852-8521, Japan.
7 Department of Physics, Department of Chemistry, Department of Material Science and Engineering and Center for 2-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania, 16802, USA.