Both the plasmon refractive index (RI) sensitivity and SERS performance of individual Au nanobipyramid (NBP) dimers are numerically investigated by finite element method (FEM). Each of the fractional shift of LSPR peak wavelength \(\lambda_{LSPR}\) of Au NBP dimer’s longitudinal dipole mode and the corresponding RI sensitivity factor \(S\) is unveiled to obey the universal “plasmon ruler” only for the scaled gap size being larger than 0.10, which is well elucidated in terms of the fractional shift of enhanced \(\left| E \right|_{\max }\) around the gap region. The maximum \(S\) and SERS enhancement factor G at gap distances 2 nm of Au NBP dimer are demonstrated to reach 618 nm RIU⁻¹ and 4.5 × 10¹¹, respectively, providing excellent plasmon RI sensitivity and SERS substrates. The enhanced S and G of Au NBP dimer than those of Au nanorod and nanoellipsoid counterparts under the same incident light and dimer geometry configurations are presented and discussed as well, respectively. The present work provides helpful clues for future designing Au dimer-based SERS substrates and LSPR RI sensors for chemical/biological sensing and detection.

通过有限元方法（FEM）数值研究了单个金纳米双锥体（NBP）二聚体的等离子体激元折射率（RI）敏感性和SERS性能。Au NBP二聚体的纵向偶极子模式的LSPR峰值波长\（\ lambda_ {LSPR} \）的分数位移和相应的RI敏感因子\（S \）中的每一个都被揭示为服从通用的“等离尺”间隙大小大于0.10，这在间隙区域周围增强\（\ left | E \ right | _ {\ max} \）的分数偏移方面得到了很好的阐明。Au NBP二聚体的间隙距离2 nm处的最大\（S \）和SERS增强因子G已证明达到618 nm RIU ^-1和4.5×10 ¹¹分别提供出色的等离激元RI敏感性和SERS底物。分别介绍和讨论了在相同的入射光和二聚体几何构型下，Au NBP二聚体比Au纳米棒和纳米椭圆体对应物增强的S和G。本工作为将来设计基于Au二聚体的SERS底物和LSPR RI传感器提供了有用的线索，以用于化学/生物传感和检测。