Laser-nanostructured Ag films as substrates for surface-enhanced Raman spectroscopy

Pulsed-laser 248 nm irradiation of Ag thin films was employed to produce nanostructured Ag/SiO2 substrates. By tailoring the laser fluence, it was possible to controllably adjust the mean diameter of the resultant near-spherical Ag droplets. Thin films of tetrahedral amorphous carbon ta-C were subsequently deposited onto the nanostructured substrates. Visible Raman measurements were performed on the ta-C films, where it was observed that the intensity of the Raman signal was increased by nearly two orders of magnitude, when compared with ta-C films grown on nonstructured substrates. The use of laser annealing as a method of preparing substrates, at low macroscopic temperatures, for surface-enhanced Raman spectroscopy on subnanometer-thick films is discussed. © 2006 American Institute of Physics. DOI: 10.1063/1.2178387