In situ surface-enhanced Raman spectroscopy of monodisperse silver nanowire arrays

Abstract

Highly ordered two-dimensional arrays of monodisperse coinage metal nanowires embedded in an alumina matrix have been prepared. When light is propagating in the direction of the long axis of the nanowire, plasmon-enhanced absorption and light guidance of the nanowire were observed by optical microspectroscopy and scanning near-field optical spectroscopy and compared to Mie scattering theory. By selectively dissolving the matrix at a constant etching rate, we detected in situ and ex situ the surface-enhanced Raman scattering (SERS) of organic dyes. In contrast to earlier publications, we find that the SERS signal is linearly proportional to the free-surface area of the nanowires that are in contact with the dye. We cannot detect any change in the enhancement factor due to the releasing of the nanowires from the host structure.