Photoelectron spectroscopy and microscopy of carbon nanotubes

In this review we will focus our attention on the characterization of carbon nanotubes by X-ray photoelectron spectroscopy. In contrast to other spectroscopic techniques, photoelectron spectroscopy allows to obtain information on the overall electronic structure of the sample in a wide energy range, which makes it a unique technique. We will discuss the most recent and the most significant results on the intrinsic electronic properties of carbon nanotubes obtained with photoelectron spectroscopy. Furthermore, we will discuss in detail the application of photoelectron microscopy, i.e. photoelectron spectroscopy with high lateral resolution, to the study of carbon nanotubes. This technique allows to obtain laterally resolved spectroscopic information from ensembles of carbon nanotubes, but it even allows to perform photoelectron spectroscopy on single carbon nanotubes.