The Multipolar Contribution and Plasmon Hybridization in Core–Shell Clusters.

Core–shell structures exhibit excellent versatility, tunability, and stability due to the different material compositions. Here, we synthesized the core–shell structure (SiO2@Au) by sol–gel method and measured the scattering spectra of its monomer, dimer, and trimer by dark field technique. Meanwhile, the contribution of multipole moments to the scattering cross-section is discussed by Mie theory. The simulated total scattering cross-section mainly contributed by electric dipole moments is in good agreement with the experimental spectra. We also found that the inner surface charge of gold shells changes significantly at different wavelengths of linearly polarized light as well as at different circularly polarized light. The asymmetric trimer with a core–shell structure has a more significant chiral response than the gold trimer. Meanwhile, there is a significant electric field enhancement at the slit between particles. This is especially useful for surface-enhanced Raman spectroscopy and the detection of trace chiral molecules. [ABSTRACT FROM AUTHOR]