Fabrication of gold nanorod arrays by templating from porous alumina

A simple procedure for fabrication of gold films with nanorod arrays is described. The method is based on thermal evaporation of gold onto a porous alumina (PA) membrane used as a template. The gold films were obtained after removing the template and characterized using scanning electron microscopy, atomic force microscopy and ultraviolet-visible spectrophotometry. The prepared gold films are composed of arrays of sharp (< 20 nm at apex) rod-shaped gold nanostructures. These structures closely follow the organization and distribution of pores of the PA template. The length of the gold nanostructures is estimated to range from 300 nm to more than 1000 nm. It was found that their length is influenced by the size of the pores in the PA and the temperature of the PA during gold evaporation. Spectrophotometric characterization shows that the prepared gold films exhibit a surface plasmon resonance absorption peak located between 525 and 540 nm.