Deep-ultraviolet surface plasmon resonance of Al and Al_core/Al₂O_3shellnanosphere dimers for surface-enhanced spectroscopy

Abstract

The localized surface plasmon resonance properties of Al and Alcore/Al2O3shell nanosphere dimers with Al and Al core nanosphere radii of 20 nm and Al2O3 shell of 2 nm in the deep-ultraviolet region have been studied using the finite difference time domain method. The extinction spectra and the electric field distribution profiles of the two dimers for various gap distances between two individual nanospheres are compared with those of the corresponding monomers to reveal the extent of plasmon coupling. It is found that with the interparticle distance decreasing, a strong plasmon coupling between two Al or Alcore/Al2O3shell nanospheres is observed accompanied by a significant red shift in the extinction spectra at the parallel polarization direction of the incident light related to the dimer axis, while for the case of the perpendicular polarization direction, a weak plasmon coupling arises characterized by a slight blue shift in the extinction spectra. The electric field distribution profiles show that benefiting from the dielectric Al2O3 shell, the gap distance of Alcore/Al2O3shell nanosphere dimers can be tailored to < 1 nm scale and results in a very high electric field enhancement. The estimated surface-enhanced Raman scattering enhancement factors suggests that the Alcore/Al2O3shell nanosphere dimers with the gap of < 1 nm gave rise to an enhancement as high as 8.1 × 107 for interparticle gap = 0.5 nm. Our studies reveal that the Alcore/Al2O3shell nanosphere dimers may be promising substrates for surface-enhanced spectroscopy in the deep-ultraviolet region.

Assessing Interparticle Spatial Characteristics of DNA-Linked Core–Shell Nanoparticles with or without Magnetic Cores in Surface Enhanced Raman Scattering

“…We have recently reported the interparticle plasmonic coupling responsible for SERS signal amplification as a result of formation of interparticle duplex DNA with gold nanoparticles, revealing a “squeezed” interparticle spatial characteristic in which the duplex DNA-defined distance is shorter than A-form DNA conformation . Similar studies were also reported, including the analysis of Au–Ag nanodimers that demonstrated a stronger SERS intensity at a lower interparticle distance than expected, − and the enhanced NP coupling with magnetic particles due to dipolar interactions in addition to the axis orientation. , Despite these studies, how this type of interparticle interaction is operative for plasmonic nanoparticles containing magnetic component remains unclear. Recent studies have employed simulation methods and SQUID technique to address this issue. , For example, Fan et al showed that the SERS intensity of Ag–Fe 3 O 4 nanocomposites was dependent on the external magnetic field and the gap distance between Ag and Fe 3 O 4 NPs .…”

Effects of thickness & shape on localized surface plasmon resonance of sexfoil nanoparticles

“…[7] This high intensity electric field (E-field) on the surface of the metal nanoparticle can be applied in surface-enhanced Raman scattering (SERS). [8][9][10] And because of their plasmonic properties, the noble metal nanoparticles can be used as components in a diverse range of technologies such as waveguides, [11] molecular rulers, [12] and photonic circuits. [13] Moreover, the LSPR spectrum of a nanoparticle is sensitive to the dielectric constant of the surrounding environment and is widely used in chemical/biological sensors.…”