Plasmon Tunability and Field Enhancement of Gold Nanostar

Objective: The localized surface plasmon resonance (LSPR) and field enhancement of Gold nanosphere and nanostar were evaluated. Method: FDTD solutions, a product of Lumerical solutions Inc., Vancouver, Canada [17], was used to perform the electromagnetic simulations in this work. The impact of particle size and spike number on peak wavelength was studied quantitatively. Result: By altering the particle size and amount of spikes, we were able to detect a hot zone around nanostar. For Au nanostar, the peak wavelength for nanostar varies from visible to near-infrared. When compared to a nanosphere of the same dimension, the shift seen in nanostar is substantially higher, making it more suitable for biosensing applications. When the refractive index of the surrounding medium is increased, a red shift in peak wavelength is noticed, forming the basis for a plasmonic refractive index sensor. Aside from having a higher sensitivity, nanostar has a twofold hot spot system due to their unique surfaces. There is no evidence of spike aggregation in the near field pattern. As a result, it is thought to be a better nanostructure for biosensing applications. Conclusion: The LSPR and field enhancement for Au nanosphere and Nanostar were investigated using the FDTD method. The nanosphere's peak wavelength is in visible region, whereas the nanostar's range extends from visible to near-infrared, depending on the size and number of spikes. At 517 nm, the enhancement factor for a nanosphere was 10², but at 1282 nm, the enhancement factor for a nanostar with six spikes was 10⁸.