X-ray photoelectron microscopy of the C 1s core level of free-standing single-wall carbon nanotube bundles

Core level photoemission spectra from a free-standing bundle of single-wall carbon nanotubes have been measured using a high-flux soft x-ray spectromicroscope. The good signal-to-noise ratio for the C 1s emission provides information on fundamental quantities such as the core-hole lifetime and binding energy, free from uncontrolled interactions between the nanotubes and the substrate or between the nanotubes and contaminants. We show that it is possible to distinguish chemically different nanotubes from the binding energy and line shape of the C 1s core level. This finding opens unique opportunities to probe in situ the response of the nanotube electronic properties and chemical activity to mechanical actions, doping, and functionalization.