Surface enhanced Raman scattering of nanoporous gold: Smaller pore sizes stronger enhancements

The authors report the surface enhanced Raman scattering (SERS) of nanoporous gold with nanopore sizes ranging from 5 to 700 nm. Their comprehensive investigations prove that the strongest SERS enhancement of nanoporous gold takes place from the samples with an ultrafine nanopore size of similar to 5-10 nm. Both the enhancement factor and detection limit of the ultrafine nanoporous substrate are one to two orders of magnitude better than those of coarsened nonporous gold with smooth surfaces. Moreover, careful microstructure characterization reveals that the anomalous SERS enhancement of the annealed nanoporous gold arises from roughsurfaces with characteristic surface irregularities. (c) 2007 American Institute of Physics.