Speaker
Description
Surface-enhanced Raman scattering (SERS) is a powerful spectroscopic technique that exploits plasmon-induced electromagnetic field enhancement on metallic nanostructures to reveal detailed molecular information from very small numbers of molecules. However, most SERS studies focus on the spectral region below 2000 cm⁻¹, while higher-order vibrational features such as overtones and combination bands remain largely unexplored despite their potential to provide additional insight into molecule-metal interactions.
Here, we demonstrate that these weak spectral features can serve as sensitive probes of molecular transformations and complex formation at plasmonic metal surfaces. As a model system, 4-aminobenzenethiol (4-ABT) adsorbed on highly enhancing silver substrates was investigated using excitation wavelengths of 455, 532, 633, and 780 nm.
By reconstructing high-order spectral features from fundamental molecular vibrations, we identify the origin of bands beyond the conventional SERS range. The results show that these transitions arise from surface-generated 4,4′-dimercaptoazobenzene (4,4´-DMAB) rather than the original 4-ABT molecules. Their excitation-wavelength dependence reflects changes in surface transformation efficiency and in the electronic properties of the adsorbed molecular species [1].
The observation of these normally weak vibrational signatures in a non-resonant system reveals how molecule-metal interactions can modify optical responses and activate new scattering pathways. These findings demonstrate that spectral regions above 2000 cm⁻¹, often neglected in routine SERS analysis, contain valuable information about surface chemistry, molecular transformations, and light-matter interactions at plasmonic interfaces.
References
[1] Kopal I.; Kmetík, M.; Matějka, P.; Piliarik, M.; Dendisová, M. Reconstructing High-Order SERS Transitions in an Overlooked Spectral Region Reveals Surface Complex Formation, Commun. Chem. 2026, Article in press.