Surface-enhanced nonresonance Raman scattering from size- and morphology-controlled gold nanoparticle films

Gold nanoparticle films with different particles sizes (35 +/- 5, 15 +/- 1 nm) and agglomerated states were prepared on glass substrates, by salting-out the colloidal solutions with NaClO4 or NaOH. An ethanol solution of rhodamine 6G was cast on the gold nanoparticle film and the surface-enhanced Raman scattering (SERS) spectrum was measured. We found that the intensity of the SERS signal was higher for the film with larger particles and that the film prepared from NaClO4 gave higher SERS signals than that prepared from NaOH. Considerable coalescence of larger gold nanoparticles was quite effective for obtaining larger SERS signals. The SERS enhancement factor was estimated to be similar to10(8) for the film prepared from NaClO4.