SERS Investigation of Rhodamine B molecule using self-assembly of nanoparticles on silanized surface

Self-assembly of silver nanoparticles on functionalized glasses via APTES was used to fabricate SERS substrates. For this purpose, silver nanoparticles were synthesized by the wet chemical method and the size distribution of 35 nm was determined, using dynamic light scattering DLS. UV-Vis spectroscopy was used to characterize the optical properties of the colloidal nanoparticles and also the prepared substrate. The results show that the surface plasmon resonance SPR peaks indicate a slight red shift after the self-assembly of nanoparticles. The SEM images showed a uniform distribution of silver nanoparticles on the surface of the glass. Rhodamine B RB dye was used as the analyte for studying substrate performances in SERS. However, no significant signals were observed in the Raman spectra of powder and solutions of the RB molecule due to a fluorescence background but using the prepared substrate and its fluorescence quenching effect, the Raman modes were clearly detected in a 10-5 M solution. By decreasing the concentration of the solution to 10-6 M, the Raman peak intensities were greatly reduced in a way that only some of them were detected.