Evidence of dynamic pentagon-heptagon pairs in single-wall carbon nanotubes using surface-enhanced Raman scattering

Surface-enhanced Raman scattering (SERS) was applied to detecting pentagon-heptagon pairs, the so-called Stone-Wales defect, in single-wall carbon nanotubes (SWCNTs). When a probing laser light was scanned over a SWCNT-dispersed silver surface, two distinct SERS spectra were obtained: (1) temporally stable spectra similar to that of resonance Raman spectra of bulk SWCNTs and (2) temporally fluctuating spectra with additional peaks which were not observed in the non-SERS spectra. The fluctuations in the SERS spectra are discussed in association with dynamic reconstruction of defective structures of SWCNTs (nonhexagonal arrangements of carbon atoms) in the vicinity of SERS-active sites under irradiation of the laser light.