At this point, we can already hypothesize that efficient Auger scattering suppresses the interband PL and, on the other hand, generates excited conduction band electrons that produce intraband PL. Auger scattering is recognized as the primary nonradiative decay route for d-band holes in noble metals, and is responsible for their short lifetimes. Disorder 58-60 and confinement are known to enhance Auger scattering in semiconductor nanostructures, due to an increased carrier density in confined systems and a relaxation of momentum conservation. As optically excited charges in metal nanostructures tend to concentrate in regions with a high aspect ratio, we speculate that the irregular structure of our AuNFs has a similar effect of increasing the Auger recombination of d -band holes, which in turn reduces the already weak interband PL even further.