Isotope-Engineered Single-Wall Carbon Nanotubes; A Key Material for Magnetic Studies

Abstract

Common catalysts for single-wall carbon nanotube (SWCNT) synthesis have magnetic components, even after extensive purification. This prevents their use in key experimental studies such as nuclear magnetic resonance spectroscopy and studies on the as-yet unresolved question of superconductivity and encapsulated single-molecule magnets in SWCNTs. Thus, there is a pressing need for SWCNT samples with no foreign magnetic components. Experimental spectroscopic and microscopy findings confirm that we have directly synthesized high-quality isotope-engineered SWCNTs with controllable and well-defined narrow diameter distributions. Purities better than 70% are obtained with optimization. Additionally, novel isotope effects were observed. Electron spin resonance studies explicitly show magnetization levels below the instrument limits, and superconducting quantum interference device studies show no magnetic component. The obtained SWCNTs succesfully meet a broad set of criteria, making them highly suited to a variety of important studies that will significantly advance our knowledge of SWCNTs.

Intertube effects on one-dimensional correlated state of metallic single-wall carbon nanotubes probed by C13 NMR

“…26 remains unknown, it might be attributed to an enhanced defect concentration in the sample, which was produced by laser ablation with nonmagnetic Rh and Pt as catalysts. 45 This method has a disadvantage of giving a low yield of SWCNTs, which leads to a large defect concentration. The GD ratio for the sample inferred from Raman scattering experiments was reported to be as high as 20, whereas it was more than 100 for the e-DIPS sample.…”

On the efficiency of bile salt for stable suspension and isolation of single-walled carbon nanotubes—spectroscopic and microscopic investigations

“…Raw SWCNTs used in this experiment were synthesized via the laser ablation technique using Pt/Re/Rh as catalysts [9]. The purification of the raw SWCNTs was accomplished via the following route: (1) annealing in air for 1 h at 300°C, (2) refluxing in diluted aqua regia for 24 h, (3) annealing at 1000°C under high vacuum (∼10 −5 mbar).…”

Enhanced π-π interactions between a C60 fullerene and a buckle bend on a double-walled carbon nanotube

“…Prior to the filling process they were purified and opened by annealing in air at 653 K for 60 min [14]. The peapods were prepared by the hot vapor filling method [12]; high purity fullerenes (MER Corp.) mixed with the opened SWNTs were heated in a sealed quartz tube under high vacuum (10 -7 hPa) at 723 K for 5 days.…”