A simple method for fabricating SERS-active substrate using Au nanoparticles is reported. HSCH2CH2NH2 was self-assembled on the Au/glass substrate, then nanoparticles of colloidal gold were bound to the surface. The SERS effect of such prepared substrate was studied by using BPE and an azobenzene thiol derivated compound and the SERS enhanced factor was found about 3×103.
Applying the Au/PATP/Au nanoparticles sandwich structUre as the model system, a semi-quantitative study on the SERS intensity with the size of Au nanoparticles has been performed. It shows that the SERS intensity increases with the size of Au nanoparticles from 15. 7nm to 66. onm. The above trend agrees with the calculated value by Schatz, while the SERS enhancement factor is 2-3 orders of the calculated value.
Gold nanoparticles were assembled on gold substrates with the self-assembled monolayer(SAM) of p-minothiophenol(PATP). AFM measurements disclose that gold nanoparticles are scattered over the surface of the substrate with a submonolayer coverage. The Raman signal of the coupling layer, the SAM of PATP, can be well observed. Potential-dependent measurements were performed to study the chemical enhancement in SERS of such a system. Based on the supposition that the direction of charge transfer is from gold nanoparticles to PATP, it is deduced that Herzberg-Teller contribution has ruled in the SERS of such a system.
