SERS and RI sensing properties of heterogeneous dimers of Au and Si nanospheres

Heterogeneous dimers of Au and Si nanoparticles are expected to exhibit different plasmon properties from that of homogeneous noble metal nanoparticle dimers. It is crucial to unveil the potential applications in surface-enhanced Raman scattering (SERS) and refractive-index (RI) sensing of the prototype dimer of Au and Si nanospheres. The near-field coupling between the two components within the dimer is revealed to not affect the resonance energy of Si mode in the extinction spectra, but decrease that of Au mode. It also accounts for the plasmon ruler behavior of the fractional shifts of both its dipolar peak wavelength of localized surface plasmon resonance (LSPR) and corresponding RI sensitivity factor S, which provide another kind of substitute to estimate the gap distance in between components within the dimer as that of noble metal nanoparticle dimers. Additionally, by tracking the inflection point shift of the corresponding extinction spectra, its S is revealed to improve 36% than that of traditional one. The maximum S and SERS enhancement factor G at 2 nm gap distance are demonstrated to reach 336 nm RIU-1 and 6.2 x 10(7), respectively. This work paves a new way for developing efficient SERS and RI sensing substrates by combining noble metal and dielectric nanoparticles.

Automated summary

The study investigates the plasmon properties of heterogeneous dimers of Au and Si nanoparticles, revealing their potential applications in SERS and RI sensing. A new approach to estimating the distance between components within the dimer is proposed.