Colloidal Au and Au/Ag nanoparticles prepared by laser ablation in liquid as a substrate of surface enhanced Raman scattering (SERS) in ascorbic acid detection

Gold (Au) and silver (Ag) nanoparticles had been successfully synthesized using a laser ablation method in distilled water. Ascorbic acid was used as the analyte to test the character of their surface enhanced Raman scattering (SERS). The concentrations of ascorbic acid were varied to study the detection limit and the incubation time effect. The size of synthesized Au and Ag nanoparticles was measured by UV-Vis spectrophotometer. The Raman scattering spectra were analyzed on 3 mL Au colloidal nanoparticles with addition of ascorbic acid in various concentrations of 0.25, 0.5 and 1 wt%. The solutions were incubated for 3 hour in room temperature prior to the Raman spectroscopy for ensuring good adsorption of ascorbic acid into the nanoparticles surface. The results were then compared with the sample using Au/Ag colloidal mixture nanoparticles incubated for same length time. The experimental results showed that the Au/Ag colloidal substrate shows more SERS sensitive for ascorbic acid signal detection compared to the Au colloidal substrate without Ag colloidal nanoparticle addition.