Abstract: Gold colloids prepared through chemical reduction were self-assembled on the surface of quartz slide to form Au colloidal films. The obtained Au colloidal films were immersed into the mixture of silver enhancer and initiator to fabricate Au core-Ag shell nanoparticles films. The optical characteristics and surface morphology of Au core-Ag shell nanoparticles films prepared under different conditions were characterized by means of UV-Vis spectroscopy and atomic force microscopy. The performance of these Au core-Ag shell nanoparticles films used as SERS-active substrates was evaluated using crystal violet as a molecular probe by the measurement of corresponding surface enhanced Raman spectrum (SERS). It was found that both the distribution of Au colloidal particles on the surface of quartz and the reaction time significantly influence the formation of Au core-Ag shell nanoparticles films. The research results indicate that the Au core-Ag shell nanoparticles film with suitable particles size and good SERS activity can be obtained by controlling the reaction condition.

Key words: Gold nanoparticle, Au core-Ag shell nanoparticle, SERS, Electrostatic self-assembly, Nanoparticles film