Effects of the rotation angle on surface plasmon coupling of nanoprisms

Abstract

We studied the effects of relative orientation of bowtie nanostructures on the plasmon resonance both experimentally and theoretically in this work. Specifically, we fabricated gold bowtie nanoantennas with rotated nanoprisms, measured the near-field and the far-field resonance behaviors using Raman spectroscopy and scattering microspectroscopy, and simulated the effects of the rotation angle on the localized surface plasmonic resonance using finite-difference time-domain simulations. In addition to the widely-discussed dipolar resonance in regular bowtie nanostructures, defined as tip-mode resonance in the present study, the excitations of edge-mode resonance were discovered under certain rotation angles of nanoprisms. Because of the resonances of different modes at different wavelengths, two different incident laser sources were used to measure the Raman spectra to provide evidence for the evolution of different resonance modes. Also, both the tip-mode and edge-mode resonances were verified by the simulated charge density distribution and their trends were discussed. Based on the discovered trend, a plasmon protractor was created with a near-exponential decay relationship between the relative resonance wavelength shift and cosine of the rotation angle. A plasmon hybridization model was also proposed for rotated bowties to explain the coupling between nanoprisms during rotation.

Achieving biosensing at attomolar concentrations of cardiac troponin T in human biofluids by developing a label-free nanoplasmonic analytical assay

“…(ii) TNPs demonstrate strong EM-field enhancement at their sharp tips and edges [38][39][40] and are thus capable of providing higher sensitivity than spherical gold nanoparticles or nanorods. 6 Although nanostars could provide better sensitivity 41 due to the presence of multiple arms with sharp tips in their structure, controlling the overall size and arm length is extremely difficult.…”

Free-standing gold elliptical nanoantenna with tunable wavelength in near-infrared region for enhanced Raman spectroscopy

“…The maximum enhancement can be achieved as the periodic distance in the polarization direction matches the incident wavelength for the bowtie structure [6]. For different plasmonic applications, the resonance wavelength can be tuned via the materials [18], particle sizes [19], arrangement [20,21], or geometries [22] of the antenna. To support the resonant mode in the near-infrared region for the medical and the communication applications, some nanostructures such as the nanocube [23] and ellipsoid particles [7] have been considered.…”

The Aggregation of Destabilized Ag Triangular Nanoplates and Its Application in Detection of Thiram Residues

“…Various assembly structures can result in different plasmonic coupling modes, so understanding the influence of various assemblies on LSPR is crucial for designing and optimizing sensors based on TNPs. Nevertheless, most studies focus on the planar assembly forms, such as bowtie nanostructure [17][18][19], coplanar nanoprism dimers with different rotation angles [20], edge-to-edge and plane-to-plane assemblies [21][22][23][24], but few have addressed three-dimensional assembly forms. Hence, it is still unclear how three-dimensional assembly forms affect Ag TNPs' optical properties.…”