基于贵金属纳米粒子在折射率传感及探测中的应用, 本文运用离散偶极近似, 模拟计算了单一金纳米棒的远场消光光谱, 研究了其偶极局域表面等离子体共振波长的可调性及折射率的传感特性。研究表明, 通过调控金纳米棒的长径比, 纳米棒的局域表面等离子体共振波长在可见至近红外波长范围内广泛可调;在可见与近红外波长范围内, 该共振波长及对应的折射率灵敏度对纳米棒长径比的响应皆分别呈现出二次与线性的分段特征。此外, 利用金介电函数虚部随入射光波长的变化关系, 揭示了金纳米棒表面等离子体所对应的半高宽随该共振波长的变化规律;并利用长径比对金纳米棒的品质因子进行了优化, 得到了优化的长径比。本文的研究结果对未来设计和制造性能优异的基于局域表面等离子体共振的传感/探测基底和元器件具有重要的理论指导意义。

Motivated by the wide applications of noble metal nanoparticles in refractive index sensitivities and detections, the tunability of dipolar peak wavelengths of localized surface plasmon resonances(LSPRs), and the refractive index sensitivities of individual Au nanorods are numerically investigated by calculating the corresponding far-field extinction spectra using discrete dipole approximation(DDA).The results indicate that the concerned dipolar LSPR peak wavelengths can be tuned from visible to near infrared by tailoring the aspect ratio of the nanorod, which respond to the aspect ratio quadratically and linearly at visible and near infrared wavelengths, respectively.Similar responses are observed for the corresponding refractive index sensitivities.Additionally, the full width at half maximum(FWHM) of the LSPR peak is understood well in terms of the optical response of the imaginary part of Au dielectrics to the incident light.The figures of merits(FOM) of individual Au nanorods are optimized by their aspect ratio, which gives the optimal aspect ratio.The present work holds great promise for future designing and fabricating LSPR based sensing/detection substrates and elements.