Measuring point defect density in individual carbon nanotubes using polarization-dependent X-ray microscopy.

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).