Inelastic electron-tunneling spectroscopy of nanoporous gold films

We investigated the localized electronic properties of nanoporous gold films by using an ultrahigh vacuum scanning tunneling microscope at low temperature (4.2 K). Second derivative scanning tunneling spectroscopy shows the plasmon peaks of the nanoporous gold films, which are excited by inelastic tunneling electrons. We propose that the nanorod model is appropriate for nanoporous gold studies at the nanometer scale. These results are supported by a three-dimensional electron tomography analysis and theoretical calculations of nanoporous gold with an ellipsoidal shape.