Resonance Quantization in the Absorption Spectra of Concentric Double Gold Nanoshells: A Numerical Study

Abstract

AbstractConcentric double metallic shells (CDMSs) are strong candidates for photothermal-based therapy, wherein they utilize their tuned plasmon resonance in the near-infrared region via particle coupling factor fitting. Tuning the resonance of CDMSs to the desired near-infrared region is crucial considering the shift caused by variations in their design parameters. In this study, we investigated the effects of these parameters using full-wave electromagnetic analysis to highlight the dominant factors affecting the resonance shift in the absorption spectra of CDMSs. With systematic variations, our simulation data outlined the direct influence of the outer and inner nanoshells’ (NS2 and NS1) aspect ratios r2 and r1, respectively, on the coupling factor (rT) aptitude for resonance tuning. For example, a CDMS with r2 = r1 = 0.8 shows coupling manifestation between NS2 and NS1 with rT as low as 0.2. However, we need the value of rT to be at least 0.6 for a CDMS with r2 = r1 = 0.4. Moreover, the dominant factors of the localized surface plasmon resonance shifts were determined by examining the mismatched parameter values of the same particle and found them to be related to NS2. We demonstrated how these factors are related to the complexity of localized surface plasmon resonance peak shifting and splitting in the absorption spectra of CDMSs. Our findings are expected to greatly improve the design of nanoparticles to optimize their responses in photothermal-based applications.