Study of SERS Chemical Enhancement Factors Using Buffer Layer Assisted Growth of Metal Nanoparticles on Self-Assembled Monolayers

摘要

Surface enhanced Raman spectroscopy (SERS), with reported ultimate sensitivities of single molecule detection, is of great interest for sensor applications. Both electromagnetic and chemical enhancements (EME, CE) contribute to SERS intensities, but much more work has focused on the former mechanism. While the CE effect has been the subject of ongoing theoretical and experimental study for decades, large disparities remain in reported CE factors (CEFs), ranging from ～10 to 10~7, often explained by sample preparation inconsistencies and lack of reliable experimental models or reference systems. Some early estimates of CEFs depended upon a precise theoretical calculation of the pure EME factors (EMEFs) based on the physical structure and electronic properties of the metal support with the estimated CEFs obtained by differences between predicted and observed SERS intensities. To date no reliable, general experimental strategy appears to have been developed to isolate and quantitate these effects. Achieving accurate measurements would provide a valuable basis for accurate interpretation of SERS sensor data for varying analytes.