SERS Substrates by the Assembly of Silver Nanocubes: High-Throughput and Enhancement Reliability Considerations

Abstract

Small clusters of nanoparticles are ideal substrates for SERS measurements, but the SERS signal enhancement by a particular cluster is strongly dependent on its structural characteristics and the measurement conditions. Two methods for high-throughput assembly of silver nanocubes into small clusters at predetermined locations on a substrate are presented. These fabrication techniques make it possible to study both the structure and the plasmonic properties of hundreds of nanoparticle clusters. The variations in SERS enhancement factors from cluster to cluster were analyzed and correlated with cluster size and configuration, and laser frequency and polarization. Using Raman instruments with 633 nm and 785 nm lasers and linear clusters of nanocubes, an increase in the reproducibility of the enhancement and an increase in the average enhancement values were achieved by increasing the number of nanocubes in the cluster, up to 4 nanocubes per cluster. By examining the effect of cluster configuration, it is shown that linear clusters with nanocubes attached in a face-to-face configuration are not as effective SERS substrates as linear clusters in which nanocubes are attached along an edge.

Calculation and measurement of radiation corrections for plasmon resonances in nanoparticles

“…The investigation of SERS in these nanocube clusters has been previously reported. 19,20,42 Figure 8 presents the computational results for various nanocube edge lengths and various "gap-to-cube size" ratios. This figure presents the dependence of one of the resonance wavelengths on this ratio.…”

“…Furthermore, these radiation corrections may be valuable in the analysis of plasmon resonances in nanoparticle clusters which are typically employed in various applications, for instance, in surface enhanced Raman spectroscopy (SERS). [11][12][13][14][15][16][17][18][19][20] For this reason, the computational results for radiation corrections are presented here for face-to-face nanocube dimers for various "gap-to-cube edge length" ratios. These computational data may be useful for the deduction of gap distances between nanoparticles from extinction cross-section measurements.…”

Comparison of electric field enhancements: Linear and triangular oligomers versus hexagonal arrays of plasmonic nanospheres

“…The non-linear scaling was found to be consistent with the near-field enhancement from inter-particle coupling simulated for clusters of spheres arranged in representative observed geometries. The variations in SERS enhancement factors from clusters of nanocubes were analyzed in [15], and correlated with cluster size and configuration, as well as laser frequency and polarization, showing an increase in the reproducibility of the enhancement and an increase in the average enhancement values by increasing the number of nanocubes in the cluster, up to 4 nanocubes per cluster.…”

Atomic-Layer-Deposition Assisted Formation of Wafer-Scale Double-Layer Metal Nanoparticles with Tunable Nanogap for Surface-Enhanced Raman Scattering

“…So far, numerous efforts have been made to design various forms of noble metallic nanostructures as SERS substrates, in which colloidal solution is widely employed to systhesis the metallic nanostructures, including nanoparticles, nanocubes and nanowires 3 , 11 , 12 . These nanostructures can show an extremely large enhancement factor and even a great potential in single molecule detection 6 , 13 .…”