Surface-enhanced Raman scattering SERS is a powerful analytical technique used for the detection and identification of chemical substances at low concentrations. The intensity of the SERS peak is highly dependent on the surface chemistry of the substrate, which can influence the enhancement of the Raman signal. Several factors related to the surface chemistry can affect the intensity of the SERS peak:1. Surface morphology: The presence of nanoscale features, such as nanoparticles, nanogaps, or roughened surfaces, can significantly enhance the local electromagnetic field, leading to an increase in the SERS signal. The size, shape, and distribution of these features can greatly influence the intensity of the SERS peak.2. Surface plasmon resonance: The SERS enhancement is mainly attributed to the excitation of localized surface plasmon resonances LSPRs on the metal surface. The LSPR frequency depends on the type of metal, its size, shape, and dielectric environment. By tuning the LSPR frequency to match the excitation wavelength, the SERS intensity can be maximized.3. Metal type: The choice of metal used for the SERS substrate plays a crucial role in determining the enhancement factor. Noble metals, such as gold, silver, and copper, are commonly used due to their strong LSPR properties and chemical stability. The type of metal can also influence the affinity of the analyte molecules to the surface, which can affect the SERS signal.4. Surface functionalization: Modifying the surface with specific functional groups or ligands can improve the selectivity and sensitivity of the SERS detection. The functionalization can promote the adsorption of target molecules onto the surface, increase the local concentration of the analyte, and facilitate the formation of a charge-transfer complex, all of which can enhance the SERS signal.5. Surface cleanliness: The presence of contaminants or impurities on the surface can interfere with the SERS signal by competing for adsorption sites or by causing background signals. A clean and well-prepared surface is essential for obtaining reliable and reproducible SERS measurements.In summary, the surface chemistry of the SERS substrate plays a critical role in determining the intensity of the SERS peak. By optimizing the surface morphology, plasmon resonance, metal type, surface functionalization, and cleanliness, the sensitivity and selectivity of the SERS detection can be significantly improved.