Tuning the number of plasmon band in silver ellipsoidal nanoshell: refractive index sensing based on plasmon blending and splitting

Because of the geometric features of both rod and shell, dielectric-silver core–shell ellipsoidal nanostructure with 12–40 nm semi-major axis may bring forth four surface plasmon resonance (SPR) absorption peaks at most. Theoretical calculations based on quasi-static approximation show that there is surrounding refractive index-dependent plasmon blending and splitting in the absorption spectra, which makes the number of plasmon band of the silver ellipsoidal nanoshell is tunable. The sensitivity of the plasmon blending and splitting to the surrounding refractive index may be improved by increasing the shell thickness, aspect ratio or core refractive index. This local refractive index dependent-plasmon blending and splitting presents a new sensing picture based on tuning the number of SPR absorption peaks.