Reflectance and electrolyte electroreflectance from gold nanorod arrays embedded in a porous alumina matrix

The specular reflectance and the electrolyte electroreflectance (EER) from an array of Au nanorods embedded within an alumina matrix are reported. The nanorods were fabricated by template electrodeposition of Au into the pores of alumina formed by a two-step anodisation of Al leading to the formation of aligned nanorods with their long axes perpendicular to the surface normal. The reflectance measured as a function of the angle of incidence and polarisation state of the incident light exhibited the transverse plasmon mode with S-polarised light and both longitudinal and transverse plasmon modes with P-polarised light. The EER spectra complemented the specular reflectance data with the dominant features again being the surface plasmon modes of the Au nanoparticles. Models are presented to describe both the reflectance and electroreflectance data that show good agreement with the experimental data.