CLEO^®/Europe-EQEC 2025 Time-Coupled Mode Theory Optimized Gold Core-Shell Particles for Surface-Enhanced Infrared Absorption

Surface-enhanced infrared absorption (SEIRA) effect greatly enhances the electric field intensity in the near-field range, and can improve the absorbed signal of molecules by several orders of magnitude [1], which is an important research direction in high sensitivity mid-infrared spectroscopy. Initially, the SEIRA structure was mainly gold particle layers, which realized a non-resonance enhancement mechanism and did not adjust the plasma resonance to the infrared band, so the enhancement effect was poor [2]. Gold particles with resonant peaks in the infrared band need to be in the order of micron size, and the cost and size uniformity of preparation are major challenges. At present, the research on SEIRA structure mainly focuses on the preparation of various types of gold nanostructures on the substrate, such as gold nanorods and gold nanoslots, which can usually achieve very high enhancement effects [3]. However, SEIRA nanostructured substrates usually require complex micro-nano processing techniques and high production costs. Meanwhile, the enhancement hotspots of SEIRA nanostructured substrates are usually located at very small tips or slits, and it is difficult to achieve accurate coverage of target molecules, which seriously limits the practical application of SEIRA structure [4].