Characterization of hotspots in a highly enhancing SERS substrate

Asiala, Steven M.; Schultz, Zachary D.

doi:10.1039/c1an15432j

Cited by 77 publications

(88 citation statements)

References 40 publications

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“…Additionally the spectral response for the red and green channels crosses near 585 nm, 39 which is near the plasmon resonance frequency of aggregated nanoparticles. 40 The reference Ag SERS substrate is known to have broad resonances, 20 but with at least one resonance located in the spectral region that corresponds to red in the Bayer filter pattern.…”

Section: Resultsmentioning

confidence: 99%

“…Silver SERS substrates used for comparison were fabricated by thermal evaporation of 500 nm of Ag onto an AAO filter as previously described. 20 The AAO filter is dissolved in 0.1 M NaOH solution to produce a nanostructured Ag film that we used as a reference substrate. All films were stored under vacuum to prevent contamination and oxidation.…”

Section: Methodsmentioning

confidence: 99%

“…Anodized aluminum oxide (AAO) is one common template that enables growth of nanostructures at fixed distances. 18, 20 In the case of AAO, the template is sacrificed after the nanostructures are formed. Alternative methods include depositing metal onto a grating 24 or other pre-structured surfaces with varied surface morphologies to promote the formation of junctions and crevices.…”

Section: Introductionmentioning

confidence: 99%

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Plasmonic color analysis of Ag-coated black-Si SERS substrate

Asiala

Marr

Gervinskas

et al. 2015

Phys. Chem. Chem. Phys.

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Red-Green-Blue (RGB) dark-field imaging can direct the choice of laser excitation for Raman enhancements on nanostructured plasmonic surfaces. Here we demonstrate that black Silicon (b-Si) is a structured surface that has been shown to effectively absorb broad wavelengths of light, but also enables surface enhanced Raman scattering (SERS) when coated with silver (Ag). Coating b-Si with increasing amounts of Ag results in increased dark-field scattering at discrete frequencies associated with localized plasmon resonances. The dark-field scattering was monitored by collecting a far-field image with an inexpensive Complementary Metal Oxide Semiconductor (CMOS) camera, similar to what is available on most mobile phones. Color analysis of the RGB pixel intensities correlates with the observed SERS intensity obtained with either green (532 nm) or red (633 nm) laser excitation in SERS experiments. Of particular note, the SERS response at 633 nm showed low spectral variation and a lack of background scattering compared to SERS at 532 nm. The difference in background suggests sub-radiant (dark or Fano resonances) may be associated with the SERS response at 633 nm and a non-resonant character of SERS. These results indicate that b-Si serves a template where Ag nucleates during physical vapor deposition. Increased deposition causes the deposits to coalesce, and at larger Ag thicknesses, bulk scattering is observed. Comparison with a high enhancement Ag SERS substrate further illustrates that a high density of plasmonic junctions, or hotspots, is important for maximizing the SERS response. The randomness of the b-Si substrate and the corresponding Ag nano-features contributes to a broadband spectral response and enhancement in SERS. Metal-coated b-Si is a promising SERS substrate due to its performance and facile fabrication.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Plasmonic color analysis of Ag-coated black-Si SERS substrate

Asiala

Marr

Gervinskas

et al. 2015

Phys. Chem. Chem. Phys.

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“…The enhanced localized fields on the fractal antennas provide a platform as efficient SERS substrates. It has been shown before that the higher the density of hot-spots, the higher the total signal intensity in SERS will be [7,[34][35][36]. Raman measurements of the structures are given in Fig.…”

Section: Resultsmentioning

confidence: 99%

Validation of electromagnetic field enhancement in near-infrared through Sierpinski fractal nanoantennas

et al. 2014

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Abstract:We introduced fractal geometry to the conventional bowtie antennas. We experimentally and numerically showed that the resonance of the bowtie antennas goes to longer wavelengths, after each fractalization step, which is considered a tool to miniaturize the main bowtie structure. We also showed that the fractal geometry provides multiple hot spots on the surface, and it can be used as an efficient SERS substrate.

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“…38 Laser excitation was provided by a 632.8 nm HeNe laser. The incident beam was delivered to the sample through a 40X water-immersion objective (Olympus, NA=0.8).…”

Section: Experimental Methodsmentioning

confidence: 99%

Online SERS detection of the 20 proteinogenic l-amino acids separated by capillary zone electrophoresis

Negri

Schultz

2014

Analyst

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A sheath-flow surface-enhanced Raman scattering (SERS) detector is demonstrated to provide chemical information enabling identification of the 20 proteinogenic L-amino acids separated by capillary zone electrophoresis (CZE). Amino acids were used to illustrate the chemical specificity of SERS detection from structurally related molecules. Analysis of the SERS electropherograms obtained from the separation and sequential online detection of six groups of structurally related amino acids shows that our sheath-flow SERS detector is able to resolve the characteristic Raman bands attributed to the amine, carboxyl, and side chain constituents. The results demonstrate the chemical information available from our detector and also provide insight into the nature of the analyte interaction with the silver SERS substrate. The spectra extracted from the SERS electropherogram of a mixture containing the 20 proteinogenic L-amino acids show unique signatures characteristic to each amino acid, thus enabling identification. The results presented here demonstrate the potential of this sheath-flow SERS detector as a general purpose method for high throughput characterization and identification following separations of complex biomolecular mixtures.

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Characterization of hotspots in a highly enhancing SERS substrate

Cited by 77 publications

References 40 publications

Plasmonic color analysis of Ag-coated black-Si SERS substrate

Plasmonic color analysis of Ag-coated black-Si SERS substrate

Validation of electromagnetic field enhancement in near-infrared through Sierpinski fractal nanoantennas

Online SERS detection of the 20 proteinogenic l-amino acids separated by capillary zone electrophoresis

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