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.

中文翻译：

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Fe-Ag纳米颗粒在核壳纳米结构中的可调光学响应

核壳纳米粒子因其在生物医学、分子检测、催化剂和癌症治疗方面的潜在应用而备受关注。在这项工作中，使用离散偶极近似 (DDA) 方法研究了核壳结构中 Fe-Ag 纳米粒子的光学特性。对于不同形状和尺寸的纳米粒子，铁核涂有不同的银壳厚度。Fe@Ag 核壳纳米粒子 (NPs) 的最大波长 (λmax.) 处的吸收局域表面等离子体共振 (LSPR) 峰值在球形和长条形纳米结构的 335–387 nm 和 382–749 nm 波长范围内发现分别。观察到 LSPR 峰随着核尺寸的增加而蓝移，随着壳厚度和纵横比的增加而红移。此外，扁平纳米结构显示，与球形纳米结构相比，λmax 处的 LSPR 峰向更长的波长范围移动。30 nm 核心尺寸和 3 的纵横比针对高灵敏度和品质因数 (FOM) 进行了优化。计算结果表明，不同的 Fe-核尺寸、Ag-壳厚度和核-壳配置 Fe@Ag NPs 的形状影响吸收光谱的调谐和增强。这些发现可作为开发合成方法的基础知识，以获得适合未来应用的 Fe@Ag 核壳 NP。计算结果表明，不同的 Fe-核尺寸、Ag-壳厚度和核-壳配置 Fe@Ag NPs 的形状影响吸收光谱的调谐和增强。这些发现可作为开发合成方法的基础知识，以获得适合未来应用的 Fe@Ag 核壳 NP。计算结果表明，不同的 Fe-核尺寸、Ag-壳厚度和核-壳配置 Fe@Ag NPs 的形状影响吸收光谱的调谐和增强。这些发现可作为开发合成方法的基础知识，以获得适合未来应用的 Fe@Ag 核壳 NP。