By G.P. Thomas
A joint research team headed by Professor Wang Feng from the University of California, Berkeley, and Professor Wang Enge from the Peking University has designed a map of carbon nanotube optical transitions.
Single-walled carbon nanotubes (SWNTs) are a representation for one-dimensional (1D) nanomaterial system. They are suitable for exploring 1D physics and providing materials for photonics and nanoelectronics, thanks to their structural integrity and physical property diversity.
The research team demonstrated an extensive and precise atlas that maps the structure of SWNTs with their optical transitions by independent identification of optical transitions and chiral indices in more than 200 individual nanotubes. This atlas, which has an uncertainty of below 20 meV, can be used as a reference for nanotube photonic, electronic, and spectroscopic identification applications. The chiral index of a SWNT can be identified without any doubt if its optical resonances are known, and vice versa.
Moreover, this map paves the way to systematically study 1D many-body phenomena in SWNTs of various diameters and types. The systematic study of the optical resonance changes induced by the electron-electron interplay in various nanotubes showed that renormalization of Fermi velocity in metallic SWNTs is the same in semiconducting SWNTs. However, Fermi velocity renormalization monotonically increases with diameter of nanotube towards the 2D graphene limit.
This strange behavior represents a perfect cancellation of diameter dependent short-range electron-electron interplay effects and long-range electron-electron interplay effects. This exotic behavior is by and large significant for differing low-dimensional materials. The map can be used as a valuable reference for next-generation energy-related applications.