scholarly journals Influence of SERS Activity of SnSe2 Nanosheets Doped with Sulfur

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1910
Author(s):  
Yuan Tian ◽  
Haonan Wei ◽  
Yujie Xu ◽  
Qianqian Sun ◽  
Baoyuan Man ◽  
...  
Keyword(s):  
Level Structure ◽  
Enhancement Effect ◽  
Practical Application ◽  
Energy Level Structure ◽  
Sers Substrates ◽  
Semiconductor Compounds ◽  
Sers Detection ◽  
Semiconductor Nanomaterials ◽  
Vibration Coupling ◽  
Important Significance

The application of 2D semiconductor nanomaterials in the field of SERS is limited due to its weak enhancement effect and the unclear enhancement mechanism. In this study, we changed the surface morphology and energy level structure of 2D SnSe2 nanosheets using different amounts of S dopant. This caused the vibration coupling of the substrate and the adsorbed molecules and affects the SERS activities of the SnSe2 nanosheets. SERS performance of the 2D semiconductor substrate can effectively be improved by suitable doping, which can effectively break the limitation of 2D semiconductor compounds in SERS detection and will have very important significance in the fields of chemical, biological, and materials sciences. In this work, the intensities of SERS signals for R6G molecules on SnSe0.93S0.94 are 1.3 to 1.7 times stronger than those on pure SnSe2 substrate. It not only provides a new way to effectively improve the SERS activity of a semiconductor SERS substrates but also helps to design more efficient and stable semiconductor SERS substrates for practical application.

Energy level structure of Sc42

1965 ◽  
Vol 62 (3) ◽  
pp. 434-448 ◽  
Author(s):  
J.W. Nelson ◽  
J.D. Oberholtzer ◽  
H.S. Plendl
Keyword(s):  
Energy Level ◽  
Level Structure ◽  
Energy Level Structure

scholarly journals Facile Detection and Quantification of Acetamiprid Using a Portable Raman Spectrometer Combined with Self-Assembled Gold Nanoparticle Array

Chemosensors ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 327
Author(s):  
Panxue Wang ◽  
Yan Sun ◽  
Li Wang ◽  
Xiang Li ◽  
Miaomiao Liu ◽  
...  
Keyword(s):  
Gold Nanoparticle ◽  
Correlation Coefficients ◽  
Nanoparticle Array ◽  
Sers Signal ◽  
Sers Substrates ◽  
Specificity And Sensitivity ◽  
Exciting Opportunity ◽  
Sers Detection ◽  
Self Assembled ◽  
Detection And Quantification

Rapid and facile determination of pesticides is critically important in food and environmental monitoring. This study developed a self-assembled gold nanoparticle array based SERS method for highly specific and sensitive detection of acetamiprid, a neonicotinoid pesticide that used to be difficult in SERS analysis due to its low affinity with SERS substrates. SERS detection and quantification of acetamiprid was conducted with self-assembled gold nanoparticle arrays at the interface of chloroform and water as the enhancing substrate. Since targets dissolved in chloroform (organic phase) also have access to the hot-spots of Au NP array, the developed method exhibited good sensitivity and specificity for acetamiprid determination. Under the optimal conditions, SERS intensities at Raman shifts of 631 cm−1 and 1109 cm−1 displayed a good linear relationship with the logarithm concentration of acetamiprid in the range of 5.0 × 10−7 to 1.0 × 10−4 mol/L (0.11335 ppm to 22.67 ppm), with correlation coefficients of 0.97972 and 0.97552, respectively. The calculated LOD and LOQ of this method were 1.19 × 10−7 mol/L (0.265 ppb) and 2.63 × 10−7 mol/L (0.586 ppb), respectively, using SERS signal at 631 cm−1, and 2.95 × 10−7 mol/L (0.657 ppb) and 3.86 × 10−7 mol/L (0.860 ppb) using SERS signal at 1109 cm−1, respectively. Furthermore, the developed SERS method was successfully applied in determining acetamiprid on the surface of apple and spinach. This method offers an exciting opportunity for rapid detection of acetamiprid and other organic pesticides considering its advantages of simple preparation process, good specificity and sensitivity, and short detection time (within 1 h).

Observation of Size Confinement Effects of Excitons in AgX Nanocrystals by Cryo-Energy-Filtering TEM/EELS

2003 ◽  
Vol 789 ◽  
Author(s):  
Vladimir P. Oleshko
Keyword(s):  
Interband Transition ◽  
Level Structure ◽  
Free Exciton ◽  
Equivalent Diameter ◽  
Relative Dielectric Permittivity ◽  
Uniform Size ◽  
Energy Level Structure ◽  
Size Dependent ◽  
Energy Filtering ◽  
Size Confinement

ABSTRACTThe non-uniform size-dependent contrast of AgBr0.95I0.05 nanocrystals (NCs) ranging from 22 to 80 nm in equivalent diameter (dc) observed by cryo-energy-filtering TEM is referred to predominant excitations at the surfaces and near the edges. When the fields due to surface losses reach throughout the structure, they couple and the probability for their generation becomes periodic in the NC size. Since electronic sum rules must be satisfied, the surface excitations reduce the strength of the bulk excitations. Coupling of surface and volume losses may cause oscillations of the image intensities with the NC size. The appearance of such oscillations demonstrates a size confinement of excitations of valence electrons due to contributions to the energy-level structure from carrier confinement and surface states. The imaginary part of relative dielectric permittivity derived from electron energy-loss spectra shows an enhanced intensity of the band at 4 eV for NCs with dc = 50±4 nm as compared to those of 109±7 nm in size, while the bands at 7 eV and at 10 eV appear to be suppressed. An increase of the intensity of exciton-assisted direct interband transition at 4 eV (Γ8-, Γ6- → Γ6) correlates with the size-dependent enhancement of free exciton luminescence from AgBr NCs, when their size is less than 100 nm.

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