Tailoring the Properties of Single-Wall Carbon Nanotube Samples through Structure-Selective Photochemistry

Abstract

It is known that as-grown samples of single-wall carbon nanotubes (SWCNTs) contain many different structural forms, displaying distinct optical and electronic properties. We report here that resonant near-infrared irradiation of the E11 optical transitions can induce selective covalent SWCNT functionalization in the presence of dissolved oxygen. By varying the irradiation wavelength, (n,m)-specific photochemistry is achieved. Using three different irradiation wavelengths at 955, 985, and 1130 nm, we have preferentially functionalized the (8,3), (6,5) and (7,6) species in aqueous dispersions. After irradiation, the sample’s fluorescence spectrum showed strong “hole-burning”, and the absorption spectrum was heavily and selectively distorted. Meanwhile, the Raman D/G intensity ratio increases, indicating the introduction of defects in the SWCNT sidewalls. This new approach should prove useful for applications such as spectral bar-coding, biomedical imaging, and spectral strain sensing. This new method of selective functionalization may also permit physical sorting of SWCNT mixtures.