Mixed Silver/Gold Colloids:  A Study of Their Formation, Morphology, and Surface-Enhanced Raman Activity

Rivas, L.; Sánchez-Cortés, Santiago; García-Ramos, † and J. V.; Morcillo, G.

doi:10.1021/la000557s

Cited by 255 publications

(196 citation statements)

References 34 publications

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“…It is well known that Au has lower EF values in the visible 37 and many attempts to obtain composite particles by depositing Ag on preformed Au particles have been extensively carried out. 38,39 So we hope our report could have some contributions to the research of the SERS enhancement mechanism on the Au surface.…”

Section: Introductionmentioning

confidence: 78%

Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

Wang

Chen

Dong

et al. 2006

The Journal of Chemical Physics

108

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A sandwich structure consisting of Ag nanoparticles (NPs), p-aminothiophenol (p-ATP) self-assembled monolayers (SAMs), and Ag NPs was fabricated on glass and characterized by surface enhanced Raman scattering (SERS). The SERS spectrum of a p-ATP SAM in such sandwich structure shows that the electromagnetic enhancement is greater than that on Ag NPs assembled on glass. The obtained enhancement factors (EF) on solely one sandwich structure were as large as 6.0±0.62×104 and 1.2±0.62×107 for the 7a and 3b(b2) vibration modes, respectively. The large enhancement effect of p-ATP SAMs is likely a result of plasmon coupling between the two layers of Ag NP (localized surface plasmon) resonance, creating a large localized electromagnetic field at their interface, where p-ATP resides. Moreover, the fact that large EF values (∼1.9±0.7×104 and 9.4±0.7×106 for the 7a- and b2-type vibration modes, respectively) were also obtained on a single sandwich structure of Au NPs∕p-ATPSAMs∕Ag NPs in the visible demonstrates that the electromagnetic coupling does not exist only between Ag NPs but also between Au and Ag NPs. The lower EF values on Au-to-Ag NPs compared to those on Ag-to-Ag NPs demonstrate that the Au-to-Ag coupling must be less effective than the Ag-to-Ag coupling for the induction of SERS in the visible.

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Section: Introductionmentioning

confidence: 78%

Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

Wang

Chen

Dong

et al. 2006

The Journal of Chemical Physics

108

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“…Some of the most extensively used SERS substrates are metal colloids because of their simplicity of preparation and strong Raman enhancement. [5,6] However, the use of the colloid solutions for SERS deals with important issues, like stability and reproducibility. [7] Nanostructures can also be fabricated electrochemically and with methods that allow high organization in the structure, like lithography methods and Langmuir-Blodgett technique.…”

Section: Introductionmentioning

confidence: 99%

Metal Nanoparticles Deposited on Porous Silicon Templates as Novel Substrates for SERS

Mikac¹,

Ivanda²,

Gotić³

et al. 2015

Croat. Chem. Acta

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Abstract:In this paper, results on preparation of stable and uniform SERS solid substrates using macroporous silicon (pSi) with deposited silver and gold are presented. Macroporous silicon is produced by anodisation of p-type silicon in hydrofluoric acid. The as prepared pSi is then used as a template for Ag and Au depositions. The noble metals were deposited in three different ways: by immersion in silver nitrate solution, by drop-casting silver colloidal solution and by pulsed laser ablation (PLA). Substrates obtained by different deposition processes were evaluated for SERS efficiency using methylene blue (MB) and rhodamine 6G (R6G) at 514.5, 633 and 785 nm. Using 514.5 nm excitation and R6G the limits of detection (LOD) for macroporous Si samples with noble metal nanostructures obtained by immersion of pSi sample in silver nitrate solution and by applying silver colloidal solution to pSi template were 10 -9 M and 10 -8 M respectively. Using 633 nm laser and MB the most noticeable SERS activity gave pSi samples ablated with 30000 and 45000 laser pulses where the LODs of 10 -10 M were obtained. The detection limit of 10 -10 M was also reached for 4 mA cm -2 -15 min pSi sample, silver ablated with 30000 pulses. Macroporous silicon proved to be a good base for the preparation of SERS substrates.

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“…For example, Freeman et al 20 have studied the SERS properties of Ag-clad Au nanoparticles and proposed that deposition of submonolayers of Ag on preformed colloid Au leads to altered aggregation and SERS enhancement behavior. Rivas et al 21 have studied the SERS activity of mixed silver/gold colloids and investigated the activity of these substrates at different excitation wavelengths. They think that preparation of Ag/ Au mixed colloids allows for the combination of the SERS activities of both metals in a broader interval of the electromagnetic spectrum.…”

Section: Introductionmentioning

confidence: 99%

Surface-enhanced Raman scattering of silver-gold bimetallic nanostructures with hollow interiors

Wang

Chen

Dong

et al. 2006

The Journal of Chemical Physics

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Surface-enhanced Raman scattering (SERS) activity of silver-gold bimetallic nanostructures (a mean diameter of ∼100nm) with hollow interiors was checked using p-aminothiophenol (p-ATP) as a probe molecule at both visible light (514.5nm) and near-infrared (1064nm) excitation. Evident Raman peaks of p-ATP were clearly observed, indicating the enhancement Raman scattering activity of the hollow nanostructure to p-ATP. The enhancement factors (EF) at the hollow nanostructures were obtained to be as large as (0.8±0.3)×106 and (2.7±0.5)×108 for 7a and 19b (b2) vibration mode, respectively, which was 30–40 times larger than that at silver nanoparticles with solid interiors at 514.5nm excitation. EF values were also obtained at 1064nm excitation for 7a and b2-type vibration mode, which were estimated to be as large as (1.0±0.3)×106 and (0.9±0.2)×107, respectively. The additional EF values by a factor of ∼10 for b2-type band were assumed to be due to the chemical effect. Large electromagnetic EF values were presumed to derive from a strong localized plasmas electromagnetic field existed at the hollow nanostructures. SERS activity of hollow nanostructures with another size (a mean diameter of ∼80nm) was also investigated and large EF for 7a and b2-type band are obtained to be (0.6±0.3)×106 and (1.7±0.7)×108, respectively, at 514.5nm excitation and (0.2±0.1)×106 and (0.6±0.2)×107, respectively, at 1064nm excitation. Although the optical properties of the hollow nanostructures have not yet been well studied, high SERS activities of the nanostructures with hollow interiors have been exhibited in our report.

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Mixed Silver/Gold Colloids: A Study of Their Formation, Morphology, and Surface-Enhanced Raman Activity

Cited by 255 publications

References 34 publications

Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

Surface enhanced Raman scattering of p-aminothiophenol self-assembled monolayers in sandwich structure fabricated on glass

Metal Nanoparticles Deposited on Porous Silicon Templates as Novel Substrates for SERS

Surface-enhanced Raman scattering of silver-gold bimetallic nanostructures with hollow interiors

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