Synthesis, characterization and SERS activity of Au–Ag nanorods

The formation mechanism and morphology of Au–Ag bimetallic colloidal nanoparticles depend on the composition. Ag coated Au colloidal nanoparticles have been prepared by deposition of Ag through chemical reduction on performed Au colloid. The composition of the Au100−x–Agx particles was varied from x = 0 to 50. The obtained colloids were characterized by UV–vis spectroscopy and transmission electron microscopy (TEM). The Au80–Ag20 colloid consists of alloy nanorods with dimension of 25 nm × 100 nm. The activity of these nanorods in surface enhanced Raman spectroscopy (SERS) was checked by using sodium salicylate as an adsorbate probe. Intense SERS bands are observed indicating its usefulness as a SERS substrate in near infrared (NIR) laser excitation.