Here we demonstrate, for the first time experimentally, a nanopipette action for metals using multiwalled carbon nanotubes. The process relies on electromigration forces, created at high electron current densities, enabling the transport of material inside the hollow core of carbon nanotubes. In this way nanoparticles of iron were transported to and from electrically conducting substrates.

In conclusion, we observed a series of exciton states with different wave-function symmetry in carbon nanotubes by one- and two-photon luminescence. By ab initio calculations of one- and two-photon spectra we showed that the experiments can only be interpreted in terms of excitonic effects. Based on these results we introduced a simplified cylindrical model for the excitonic states to derive exciton binding energies from two-photon experiments. We determined binding energies between 300 and 400 meV for several nanotube species. Our results demonstrate that excitonic properties dominate optical absorption and emission in carbon nanotubes even at room temperature.