Collective plasmon modes in a compositionally asymmetric nanoparticle dimer

Abstract

The plasmon coupling phenomenon of heterodimers composed of silver, gold and copper nanoparticles of 60 nm in size and spherical in shape were studied theoretically within the scattered field formulation framework. In-phase dipole coupled σ-modes were observed for the Ag-Au and Ag-Cu heterodimers, and an antiphase dipole coupled π-mode was observed for the Ag-Au heterodimer. These observations agree well with the plasmon hybridization theory. However, quadrupole coupled modes dominate the high energy wavelength range from 357-443 nm in the scattering cross section of the D=60 nm Ag-Au and Ag-Cu heterodimer. We demonstrate for the first time that collective plasmon modes in a compositionally asymmetric nanoparticle dimer have to be predicted from the dipole-dipole approximation of plasmon hybridization theory together with the interband transition effect of the constitutive metals and the retardation effect of the nanoparticle size

Ideal Dimers of Gold Nanospheres for Precision Plasmonics: Synthesis and Characterization at the Single‐Particle Level for Identification of Higher Order Modes

“…For additionally supporting our mode assignment by predictions from theory, we performed FDTD simulations. 50 nm gold spheres in combination with a 1.0 nm gap were employed as a dimer model .…”

“…For analyzing the polarization‐dependent behavior of the higher order longitudinal plasmon coupling modes in the region 500–650 nm, we subtracted the contribution from the TADP mode at 535 nm in each elastic scattering spectrum (phase shift of 90°). A closer inspection of the resulting spectra (Figure S5, Supporting Information) indicated that the region 500–650 nm comprises not only contributions from the TADP mode at 535 nm and the LBQP mode at 578 nm, but also from the longitudinal bonding octupolar plasmon coupling (LBOP) mode at 536 nm . Although the TADP and LBOP modes have nearly the same plasmon coupling energy (peaks at 535 and 536 nm, respectively), they can be unambiguously discriminated from each other due to their orthogonal polarization‐dependent behavior.…”

Nanoscale Plasmon‐Enhanced Spectroscopy in Memristive Switches

“…Turning ON the memristive switch red shifts the peak rapidly (within our current time resolution) indicating the distance between the two electrodes is reduced due to cation migration. The additional peak emerging at λ 2 = 500 nm at the same time, which blue shifts to λ 2 = 445 nm, is likely to arise from a higher‐order bonding mode between mixed Ag–Au dipole–quadrupole hybridized coupling . Reversal of the voltage restores the plasmon spectral signature to that observed at previous times.…”

Quadrupole plasmon excitations in confined one-dimensional systems

“…The quadrupole plasmon resonance modes in nanostructures have widely reported [28][29][30][31][32]. To the best of our knowledge, however, this type of plasmon excitation has not been reported in the one-dimensional cluster systems.…”