Measuring Point Defect Density in Individual Carbon Nanotubes Using Polarization-Dependent X-ray Microscopy

Abstract

The presence of defects in carbon nanotubes strongly modifies their electrical, mechanical, and chemical properties. It was long thought undesirable, but recent experiments have shown that introduction of structural defects using ion or electron irradiation can lead to novel nanodevices. We demonstrate a method for detecting and quantifying point defect density in individual carbon nanotubes (CNTs) based on measuring the polarization dependence (linear dichroism) of the C 1s --> pi* transition at specific locations along individual CNTs with a scanning transmission X-ray microscope (STXM). We show that STXM can be used to probe defect density in individual CNTs with high spatial resolution. The quantitative relationship between ion dose, nanotube diameter, and defect density was explored by purposely irradiating selected sections of nanotubes with kiloelectronvolt (keV) Ga(+) ions. Our results establish polarization-dependent X-ray microscopy as a new and very powerful characterization technique for carbon nanotubes and other anisotropic nanostructures.

Molecular Dynamics Simulation Study on the Mechanical Properties and Fracture Behavior of Single-Wall Carbon Nanotubes

“…So the need to identify and quantify them is also required. Measurements done by polarization dependent scanning transmission X-ray microscopy (Felten et al, 2010) or Raman spectroscopy (Miyata et al, 2011) can now identify and quantify defects. Defect spacing can further be varied by varying the synthesis technique (Fan et al, 2005).…”

Revealing the Role of Catalysts in Carbon Nanotubes and Nanofibers by Scanning Transmission X-ray Microscopy

“…Scanning transmission X-ray microscopy (STXM) has been considered to be an effective tool to localize and characterize the electronic structure of carbon nanomaterials891011121314. STXM combines both X-ray absorption near-edge structure (XANES) spectroscopy and microscopy with a spatial resolution of a few tens of nanometers12.…”

“…XANES is an element-specific spectroscopic technique involving the excitation of electrons from a core level to local and partial empty states of a defined character1214. The combination of classical XANES method with a high spatial resolution in STXM provides a unique capability to explore electronic and structural information in carbon nanomaterials891011121314. Here by employing STXM, Fe and Ni residues, the widely used catalyst in the CNT/CNF growth1516, in individual CNT and CNF were imaged with a concurrent identification of their electronic structure.…”

Detecting the hollow structure of thick carbon nanotubes by scanning transmission X-ray microscopy

“…[1][2][3][4] For example, an individual CNT can be used as a highly conductive wire in nano-devices. [5][6][7][8][9] The characterization of individual CNTs should be carefully considered before applications. However, CNTs prepared by the same way can be different due to various factors such as structural defects, amorphization and modication levels, or different surface contaminations.…”