Surface-enhanced Raman scattering (SERS) from Au:Ag bimetallic nanoparticles: the effect of the molecular probe

2013 ◽  
Vol 4 (1) ◽  
pp. 509-515 ◽  
Author(s):  
Meikun Fan ◽  
Feng-Ju Lai ◽  
Hung-Lung Chou ◽  
Wan-Ting Lu ◽  
Bing-Joe Hwang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Bimetallic Nanoparticles ◽  
Surface Enhanced Raman Scattering ◽  
Molecular Probe ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

scholarly journals “Coffee Ring” Effect of Ag Colloidal Nanoparticles Dried on Glass: Impact to Surface-Enhanced Raman Scattering (SERS)

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Petra Šimáková ◽  
Eva Kočišová ◽  
Marek Procházka
Keyword(s):  
Raman Scattering ◽  
Hot Spots ◽  
Surface Enhanced Raman Scattering ◽  
Molecular Probe ◽  
Colloidal Nanoparticles ◽  
Sers Signal ◽  
Coffee Ring ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

It is well known that spontaneous drying of some fluid droplets on certain solid surfaces forms a “coffee ring” pattern. In this paper, we studied “coffee ring” formation for two kinds of Ag colloidal nanoparticles (borohydride-reduced (b.-r.) and hydroxylamine-reduced (h.-r.)) and its impact on surface-enhanced Raman scattering (SERS). Optical and scanning electron microscopies were used to observe the morphology of the dried rings as well. We used 5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphyrin (TMPyP) as a testing SERS molecular probe. The results showed that the structure of the edge rings of dried drops of Ag colloid/TMPyP systems was different for b.-r. and h.-r. nanoparticles. The inherent limitation of our approach is inhomogeneity in particle and “hot spots” distribution, SERS signal fluctuation, and consequently low spectral reproducibility. However, in the case of h.-r. nanoparticles, it formed a structure with highly enhancing sites (“hot spots”) providing enormous SERS signal of TMPyP. Higher sensitivity and the possibility of spectral mapping over the dried pattern are advantages in comparison with the measurements from colloidal suspension. Although our approach is not reliable for quantitative analytical SERS applications, it can serve as a simple, cheap, and fast prescan method, which can be easily implemented for preliminary SERS analysis.

A Simple Route to Synthesize Cu@Ag Core–Shell Bimetallic Nanoparticles and Their Surface-Enhanced Raman Scattering Properties

2016 ◽  
Vol 70 (10) ◽  
pp. 1692-1699 ◽  
Author(s):  
Xia Jin ◽  
Aiqin Mao ◽  
Mengling Ding ◽  
Peipei Ding ◽  
Tianchi Zhang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Bimetallic Nanoparticles ◽  
Surface Enhanced Raman Scattering ◽  
Molar Ratio ◽  
Protective Atmosphere ◽  
Core Shell ◽  
Ag Nps ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Enhanced Raman Scattering

Water-dispersed Cu@Ag core–shell nanoparticles (NPs) with 15 nm-diameter Cu core and 5 nm-thick Ag shell can be synthesized by a facile one-step chemical reduction at room temperature without any protective atmosphere. To obtain a homogeneous Ag coating on Cu, the influence of [Cu/Ag] molar ratio was investigated. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) confirmed that Ag formed a dense coating on the surface of Cu, and that phase-pure spherical Cu@Ag core–shell bimetallic NPs were prepared when the [Cu/Ag] molar ratio was between 1/0.5 and 1/0.75. The time dependence of ultraviolet-visible (UV-Vis) spectra and XRD patterns of six-month stored Cu@Ag NPs showed that the as-prepared Cu@Ag NPs have a long-term antioxidant activity. Also, the surface-enhanced Raman scattering (SERS) signals had a high stability and reproducibility for the substrates. Hence, the as-prepared Cu@Ag nanostructures can be used as an efficient substrate for SERS signals.

Sign in / Sign up

Export Citation Format

Share Document