Abstract
We characterized the energy band dispersion near the Fermi level in single-walled carbon nanotubes using low-temperature scanning tunneling microscopy. Analysis of energy-dependent standing wave oscillations, which result from quantum interference of electrons resonantly scattered by defects, yields a linear energy dispersion near E(F), and indicates the importance of parity in scattering for armchair single-walled carbon nanotubes. Additionally, these data provide values of the tight-binding overlap integral and Fermi wave vector, in good agreement with previous work, but indicate that the electron coherence length is substantially shortened.
Highlights
The remarkable electronic properties of single-walled carbon nanotubes (SWNTs), which are due in large part to their unusual band structures [1,2,3,4,5,6,7], have aroused considerable excitement in fundamental and applied research [1,2,3]
In the case of isolated armchair (n,n) SWNTs, the πbonding (π) and π-antibonding (π*) energy bands are predicted to cross at the Fermi level (EF) in an unique linear fashion, contrasting the parabolic dependence expected from a conventional free-electron picture
Use of conventional momentum analysis methods, which average over substantial area, is difficult since SWNT samples consist of a wide range of structures each with different energy dispersions [5,6]
Summary
The remarkable electronic properties of single-walled carbon nanotubes (SWNTs), which are due in large part to their unusual band structures [1,2,3,4,5,6,7], have aroused considerable excitement in fundamental and applied research [1,2,3]. We report STM studies that elucidate the 1D energy dispersion of SWNTs by spatially resolving energy dependent standing wave oscillations near an isolated defect.
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