Estimating the Analytical and Surface Enhancement Factors in Surface-Enhanced Raman Scattering (SERS): A Novel Physical Chemistry and Nanotechnology Laboratory Experiment

A novel laboratory experiment was successfully implemented for undergraduate and graduate students in physical chemistry and nanotechnology. The main goal of the experiment was to rigorously determine the surface-enhanced Raman scattering (SERS)-based sensing capabilities of colloidal silver nanoparticles (AgNPs). These were quantified by estimating the analytical enhancement factor (AEF) and surface enhancement factor (SEF) of the AgNPs, that is, the most important values for characterizing the SERS effect. SERS is an embodiment of Raman spectroscopy that currently finds numerous cutting-edge applications. To achieve this, students synthesized a Creighton colloid and characterized its optical properties by UV–vis absorption spectrophotometry. The AEF and SEF values were then estimated from the measured Raman, SERS, and fluorescence emission spectra of a test probe, rhodamine 6G, adsorbed on the colloidal AgNPs. This laboratory experiment introduced the students to the fundamentals of SERS spectroscopy and implicitly to concepts related to light scattering, surface chemistry, and resonance effects. Furthermore, students acquired new instrumental and nanotechnology-related skills that will assist them in technologically demanding careers.