Inelastic electron tunneling spectroscopy of nanoporous gold films
  We investigated the localized electronic properties of nanoporous gold films by using an ultra-high 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 3D electron tomography analysis and theoretical calculations of nanoporous gold with ellipsoid shape. 
H. W. Liu, R. Nishitani, T. Fujita, W. Li, L. Zhang, X. Y. Lang, P.   Richard, K. S. Nakayama, X. Chen, M. W. Chen and Q. K. Xue
cond-mat.mtrl-sci