Tunable optical response of Fe-Ag nanoparticles in core-Shell nanostructures

The core-shell nanoparticles have received much attention due to their potential applications in biomedicine, molecular detection, catalyst, and cancer therapy. In this work, the optical properties of Fe-Ag nanoparticles in core-shell configuration are studied by using the discrete dipole approximation (DDA) method. The Fe-core is coated with varying Ag-shell thicknesses for different shapes and sizes of nanoparticles. The absorption localized surface plasmon resonance (LSPR) peak at the maximum wavelength (λmax.) of Fe@Ag core-shell nanoparticles (NPs) is found in the range of 335–387 nm & 382–749 nm wavelengths for sphere & prolate nanostructures respectively. It is observed that the LSPR peaks are blue-shifted with increasing core-sizes and red-shifted with the increasing shell thickness as well as the aspect ratio. Furthermore, prolate nanostructure shows the shifting of LSPR peaks at λmax towards the longer wavelength regime as compared to spherical shape nanostructures. The 30 nm core-size and aspect ratio of 3 is optimized for high sensitivity and figure of merit (FOM). The calculated results suggest that different Fe-core sizes, Ag-shell thickness, and shapes in core-shell configuration Fe@Ag NPs influence the tunning and enhancement of absorption spectra. These findings can be utilized as basic knowledge for the development of synthesis methods to obtain suitable Fe@Ag core-shell NPs for future applications.