Search

Synthesized single-walled carbon nanotubes (SWNTs) are racemic mixtures of various (n, m) species with different electronic types, which greatly impeded their practical applications and fundamental research. In this paper, achiral amino acid surfactant sodium N-cocoyl sarcosinate (N-CS) not only displayed selectivity toward s-SWNTs but also could further separate the sorted s-SWNTs by the chirality indices (n, m) and left- and right-handedness with the aid of density gradient ultracentrifugation (DGU). The specific molecular structure of N-CS offered the possibility of recognizing the left- and right-handedness of SWNTs. The enantiomer separation mechanism was illustrated by Molecular dynamics simulations. Achiral amino-acid surfactant N-CS was used to separate SWNTs by chiral indices and left- and right-handedness with the aid of density gradient ultracentrifugation [ABSTRACT FROM AUTHOR]

Single-wall carbon nanotubes (SWCNTs) have extraordinary electronic and optical properties that depend strongly on their exact chiral structure and their interaction with their inner and outer environment. The fluorescence (PL) of semiconducting SWCNTs, for instance, will shift depending on the molecules with which the SWCNT's hollow core is filled. These interaction-induced shifts are challenging to resolve on the ensemble level in samples containing a mixture of different filling contents due to the relatively large inhomogeneous line width of the ensemble SWCNT PL compared to the size of these shifts. To circumvent this inhomogeneous broadening, single-tube spectroscopy and hyperspectral imaging are often applied, which until now required time-consuming statistical studies. Here, we present hyperspectral PL microscopy combined with automated SWCNT segmenting based on either principal component analysis or a convolutional neural network, capable of both spatially and spectrally resolving the PL along the length of many individual SWCNTs at the same time and automatically fitting peak positions and line widths of individual SWCNTs. The methodology is demonstrated by accurately determining the emission shifts and line widths of thousands of left- and right-handed empty and water-filled SWCNTs coated with a chiral surfactant, resulting in four statistical distributions which cannot be resolved in ensemble spectroscopy of unsorted samples. The results demonstrate a robust method to quickly probe ensemble properties with single-enantiomer spectral resolution. Moreover, it promises to be an absolute quantitative method to characterize the relative abundances of SWCNTs with different handedness or filling content in macroscopic samples, simply by counting individual species.