Probing the dispersivity of tunable refractive index in the visible range by sensitive localized surface plasmon resonance inflection points in single gold nanorods

Abstract

Herein, under the quasi-static regime, we used localized surface plasmon resonance (LSPR) inflection points (IFs) of single gold nanorods (AuNRs) to get insightful view in their fundamental role in revealing the dispersivity and tunability of the complex refractive index (RI) of AuNRs. AuNRs exhibited broad-band RIs in the visible range with maxima near the resonance energies, and these broad-bands are even stable at long wavelengths with RIs below 1 RI unit. Furthermore, the low energy IFs with low sensitivities are associated with the highest RI (n) values, whereas the high energy IFs exhibit the highest optical extinction (k).