Highly Ordered Arrays of Particle‐in‐Bowl Plasmonic Nanostructures for Surface‐Enhanced Raman Scattering

Abstract

A highly ordered particle-in-bowl (PIB) nanostructure array is designed and fabricated to achieve large field enhancement for the surface-enhanced Raman scattering (SERS) application. This new type of PIB structure is composed of an Ag particle located at the bottom of an Au bowl, and the two are separated by a precisely controlled nanoscale dielectric layer. The fabrication of the PIB structure is based on the self-assembly of polystyrene spheres and atomic layer deposition (ALD), which allows good control of the metal particle size and gap distance, as well as large-scale ordering. Numerical simulation reveals a high enhancement of the local field at the nanogaps. The SERS performance of the PIB arrays, and the effects of the Ag particle size and the ALD dielectric layer thickness are characterized, results of which are in reasonable agreement with simulation. With Rhodmaine 6G as the probe molecule, the spatially averaged SERS enhancement factor is on the order of 3.8 × 10(7) and the local field enhancement from simulation can be up to 10(8) .

Maximizing surface-enhanced Raman scattering sensitivity of surfactant-free Ag-Fe3O4 nanocomposites through optimization of silver nanoparticle density and magnetic self-assembly

“…From the measured SERS enhancements, we can evaluate the role played by the gap size and density of Ag-NPs in different nanostructures. The Enhancement Factor (EF) 43,44 can be calculated quantitatively according to the following formula: [45][46][47] EF ¼ ðI SERS =N SERS Þ=ðI 0 =N 0 Þ; where I SERS and N SERS are the Raman peak intensity values and the total number of molecules adsorbed on the prepared substrate, and I 0 and N 0 are the corresponding parameters for the control sample (5 ll, 5 mM R6G solution deposited on a Si substrate in our experiment). This calculation is based on the fact that the intensity of the collected SERS signal is proportional to the total number of molecules if the molecules are at a low concentration level.…”

Subradiant, Superradiant Plasmon Modes and Fano Resonance in a Multilayer Nanocylinder Array Standing on a Thin Metal Film

“…The meshes have been refined until convergence and simulations run long enough to resolve all sharp features in the spectra. The dielectric constant of Ag is approximated by formula (1) according to the classical Drude model [33], where ω p is the plasma frequency and γ is the damping constant related to the dispersion of the electrons (γ =2π × 4.36 THz [21]). The plasma frequency (ω p ) is given by [33] …”

“…Metal nanoparticles [12][13][14][15][16][17] also show novel optical properties which strongly depend on their shapes, sizes, and compositions as well as the dielectric environments. Based on the theory of hybridized plasmon modes [18], complex nanostructures consisting of multilayer particles were also studied, including the most famous shell-core structures [19][20][21][22] and metal-dielectric-metal nanoparticles [20,[23][24][25]. In these complex nanostructures, subradiant modes, which cannot be directly excited by incident light, can be obtained via the coupling interaction of parent plasmons.…”

Fano resonance boosted cascaded optical field enhancement in a plasmonic nanoparticle-in-cavity nanoantenna array and its SERS application

“…Efforts were also made by other researchers regarding the fabrication of PICs by other methods, such as nanosphere lithography assisted by an oblique deposition technique and annealing treatment. [26][27][28][29][30][34][35][36][37] However, obtaining a single gold NP dressing in each nanovoid is difficult and the PIC array can only be arranged in closely packed hexagonal lattice. The randomness of the NP allocation in these fabricated PIC structures is a significant problem that substantially degrades the expected CFE effect.…”