Surface-enhanced Raman Scattering Effects Of Gold Nanorods Prepared By Polycarbonate Membranes

Surface-enhanced Raman scattering spectroscopy is a very useful technique which can enhance the Raman signal of sample molecules. It is an important tool for studying the interaction process between surface and molecules, and a powerful tool for qualitatively identifying compounds with similar chemical structures. Additionally, it can be used to distinguish isomers, and to identify different adsorption orientations of one molecule. Since it has a number of advantages, such as high sensitivity, fluorescence bleaching, and simple operation, it is widely used in chemistry, biology, medicine and food safety, etc. Based on template electrochemical deposition, we prepared gold nanorods substrates, and launched a series of researches, which is summarized as follows:1) Using a Polycarbonate Membrane (PCM) as a template, and combining with the electrochemical deposition method, we prepared gold nanorods about36nm in diameter and1μm in length.2) Measuring the transmission spectra and scattering spectra of prepared gold nanorods, we found resonant absorption peaks are around540nm and427nm, respectively for surrounded and not surrounded by polycarbonate molecules.3) The enhancement effects of the nanorods were investigated with514nm and633nm laser excitations. Comparing the spectra under resonant and non-resonant conditions, we concluded that the field enhancement effect under the resonant excitation was more prominent than that of the non-resonant excitation. The enhancement factor under the resonant excitation increased to7times of the factor under the non-resonant excitation.4) Using a prepared gold nanorods substrate, we measured the SERS spectra of rhodamine6G molecules. The result show its signal enhancement is remarkable.Comparing to similar researches, we achieved following two improvements:1) With a resonant excitation, we significantly increased the enhancement factor of gold nanorods.2) We eliminated the fluorescence of PCM molecules, thus made the template method more feasible for transparent SERS substrate applications.3) We have considered the impact of dielectric constant of surrounding medium, which provides a new way for further optimization.4) The preparation method in this paper is original, for that the prepared gold nanorods can be made into transparent SERS substrate and opaque reflecting SERS substrate as well.