Versatile Visualization of Individual Single-Walled Carbon Nanotubes with Near-Infrared Fluorescence Microscopy

Fluorescence microscopy in the near-infrared between 950 and 1600 nm has been developed as a novel method to image and study single-walled carbon nanotubes (SWNTs) in a variety of environments. Intrinsic photoluminescence of disaggregated pristine SWNTs was excited by a diode laser and detected with a two-dimensional InGaAs photodiode array. Individual nanotubes were visualized with a spatial resolution of ca. 1 microm and characterized with polarization measurements and emission spectroscopy. Spatially resolved emission spectra allowed (n,m) identification of single nanotubes and revealed small environmentally induced spectral shifts between segments of long tubes. Nanotube motions in aqueous surfactant were visualized with a time resolution of 50 ms and used to estimate the diffusion coefficient.