Toward hyperuniform disordered plasmonic nanostructures for reproducible surface-enhanced Raman spectroscopy

Abstract

We report on the self-assembling of clusters of gold-nanoparticles (Au-NPs) directed by the phase separation of poly(styrene)-b-poly(methylmethacrylate) (PS-b-PMMA) block-copolymer (BCP) on indium tin oxide coated glass, which induces the onset of vertical lamellar domains. After thermal evaporation of gold on BCP, Au-NPs of 4 nm are selectively included into PS-nanodomains by thermal annealing, and then clustered with large density of hot spots (> 10(4) μm(2)) in a random two-dimensional pattern. The resulting nanostructure exhibits near-hyperuniform long-range correlations. The consequent large degree of homogeneity of this isotropic plasmonic pattern gives rise to a highly reproducible Surface-Enhanced Raman Scattering (SERS) enhancement factor over the centimeter scale (std. dev. ∼ 10% over 0.25 cm(2)). We also discuss the application of a static electric field for modulating the BCP host morphology. The electric field induces an alignment of Au-NP clusters into ordered linear chains, exhibiting a stronger SERS activity, but reduced SERS spatial reproducibility.

Hyperuniform states of matter

“…This enabled investigators to design disordered hyperuniform cellular solids with unprecedented waveguide geometries unhindered by crystallinity and anisotropy, and robust to defects [86,87]. A variety of groups have recently fabricated various disordered hyperuniform materials at the micro-and nano-scales, including those for photonic applications [87][88][89][90][91], surface-enhanced Raman spectroscopy [92], the realization of a terahertz quantum cascade laser [93], self-assembly of diblock copolymers [94], periodically-driven emulsions [53], and selfassembled two-dimensional jammed packings of bidisperse droplets [49]. Recent computational investigations on stealthy hyperuniform systems have been directed toward optical [95], photonic [96][97][98], phononic [99], diffusion and conduction transport [83,100], and frequency-dependent dielectric constant behaviors [82][83][84] and applications.…”

Surface roughness boosts the SERS performance of imprinted plasmonic architectures

“…[5] By itself, Raman scattering is a weak phenomenon with a cross-section in the order of 10 -29 cm 2 ·molecule -1 , [6] however the signal output can be enhanced several orders of magnitude [7] by the use of nanostructured metallic supports, leading to the phenomenon known as Surface Enhanced Raman Scattering (SERS). [13][14][15] However, inter-device reproducibility and tunability of the optical properties of such substrates are lower than competing ordered geometries. [8][9][10] Since its discovery in 1974 in electrochemically roughened silver electrodes, [11] research studies in SERS substrates have focused in either random or well-ordered architectures.…”

Ensemble Theory for Stealthy Hyperuniform Disordered Ground States

“…2 for a vivid illustration. During the last decade, a variety of disordered hyperuniform states have been identified that exist as both equilibrium and nonequilibrium phases, including maximally random jammed particle packings [33][34][35][36], jammed athermal granular media [37], jammed thermal colloidal packings [38,39], cold atoms [40], transitions in nonequilibrium systems [41,42], surfaceenhanced Raman spectroscopy [43], terahertz quantum cascade laser [44], wave dynamics in disordered potentials based on supersymmetry [45], avian photoreceptor patterns [46], and certain Coulombic systems [47]. Moreover, disordered hyperuniform materials possess novel physical properties potentially important for applications in photonics [25][26][27]48,49] and electronics [50][51][52].…”