Chirality-Resolved Length Analysis of Single-Walled Carbon Nanotube Samples through Shear-Aligned Photoluminescence Anisotropy

Abstract

An efficient new method is demonstrated for measuring length distributions of semiconducting single-walled carbon nanotubes (SWCNTs) through analysis of their highly polarized photoluminescence when aligned by shear flows. Instrumentation and procedures are developed to characterize nanotube lengths in bulk suspensions with rapid data acquisition and interpretation. Applying the method with spectrally resolved SWCNT emission provides the first measurements of (n,m)-specific length distributions. A positive correlation is found between average length and nanotube diameter, although this correlation is weaker following extensive sample centrifugation. Intense sonication shortened all nanotube species and had the strongest effect on those with small diameters. The new method should provide a useful alternative to atomic force microscopy for characterizing SWCNT lengths.

Compressive dynamic scission of carbon nanotubes under sonication: fracture by atomic ejection

“…For further cutting, the (6,6) nanotube must be sonicated even longer from B 3 to B 4 than the (12,12) tube from A 2 to A 3 . However, the difference between the initial defect densities in the different diameter nanotubes can reverse the apparent dependence of the cutting rate on the diameter (Heller et al 2004;Casey et al 2008). …”

“…The most widely adopted method of cutting was introduced by Liu et al (1998) more than a decade ago and involves ultrasonication of single-walled carbon nanotubes (SWCNTs) in an aqueous medium. It was also discovered that the cutting rate under ultrasonication depends on the diameter of the carbon nanotube, and the dependence has been used for diameter sorting of the nanotubes (Heller et al 2004;Hennrich et al 2007;Casey et al 2008). Though the mechanism of cutting has been widely attributed to the collapse of cavitated microbubbles during sonication (Liu et al 1998;Heller et al 2004;Hennrich et al 2007), the nanoscale cutting mechanism of SWCNTs under ultrasonication and the associated diameter-dependent cutting rate are still not well understood.…”

Chemometric determination of the length distribution of single walled carbon nanotubes through optical spectroscopy

“…SWCNTs (8,10, and 12 mg, respectively) synthesized by CO decomposition on cobalt-molybdenum catalysts (Sigma-Aldrich, batch number 94496KJ) were dispersed in 10 mL of 2 wt% aqueous sodium deoxycholate (DOC) solution. The suspensions were sonicated in an ultrasonicator (SONICS, VCX-130) for 1 hr at 30 W in an ice bath, prior to being centrifuged at 53,000 g (Hitachi-Koki, CS150GXL) for 1 hr to remove large nanotube bundles and other impurities.…”

“…Length sorting may 1 These authors contributed equally to the presented work. also be necessary as a preliminary step to obtain high purity monodisperse samples [8,9]. Furthermore, toxicity of SWCNTs is often associated with their length.…”

“…In recent years, several techniques have been developed to sort SWCNTs by length, including size exclusion chromatography [6,11], gel electrophoresis, capillary electrophoresis, shear-aligned photoluminescence anisotropy [8], field flow fractionation [12], and density gradient ultracentrifuge (DGU) [13][14][15]. Separation of SWCNTs by length using centrifugation in a density gradient medium was developed by Fagan et al [14].…”