Tunable surface plasmon resonance wavelengths response from Au/Ag nanocomposite system

In this study, Au/Ag nanocomposite films with localized surface plasmon resonance (LSPR) tunability were prepared by thermal annealing under ambient conditions. The effects of thermal annealing on the structure, morphology, and optical properties of the samples were investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–VIS-NIR double-beam spectroscopy and Raman spectroscopy. The results show that thermal annealing transforms Au/Ag films from continuous to discontinuous porous or gaping nanostructures with red-shifted properties, which greatly increases the sensitivity of surface-enhanced Raman scattering (SERS). In addition, finite-difference time-domain (FDTD) simulations confirm the correctness of the Raman scattering results.