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The invention of TERS led to a breakthrough in the substrate and surface generalities of SERS (18,19). It uses a working mode that separates the probed substance from a Au [...], Surface-enhanced Raman scattering (SERS) is a powerful spectroscopy technique that can provide non-destructive and ultrasensitive characterization down to single molecular level, comparable to single-molecule fluorescence spectroscopy (1-15). However, generally substrates based on metals such as Ag, Au and Cu, either with roughened surfaces or in the form of nanoparticles, are required to realise a substantial SERS effect, and this has severely limited the breadth of practical applications of SERS. A number of approaches have extended the technique to non-traditional substrates (14,16,17), most notably tip-enhanced Raman spectroscopy (TERS) (18-20) where the probed substance (molecule or material surface) can be on a generic substrate and where a nanoscale gold tip above the substrate acts as the Raman signal amplifier. The drawback is that the total Raman scattering signal from the tip area is rather weak, thus limiting TERS studies to molecules with large Raman cross-sections. Here, we report an approach, which we name shell-isolated nanoparticle-enhanced Raman spectroscopy, in which the Raman signal amplification is provided by gold nanoparticles with an ultrathin silica or alumina shell. A monolayer of such nanoparticles is spread as 'smart dust' over the surface that is to be probed. The ultrathin coating keeps the nanoparticles from agglomerating, separates them from direct contact with the probed material and allows the nanoparticles to conform to different contours of substrates. High-quality Raman spectra were obtained on various molecules adsorbed at Pt and Au single-crystal surfaces and from Si surfaces with hydrogen monolayers. These measurements and our studies on yeast cells and citrus fruits with pesticide residues illustrate that our method significantly expands the flexibility of SERS for useful applications in the materials and life sciences, as well as for the inspection of food safety, drugs, explosives and environment pollutants.

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Plasmonic metals under photoexcitation can generate energetic hot electrons to directly induce chemical reactions. However, the capability and fundamental insights of the transportation of these hot electrons at plasmonic metal‐2D material interfaces remain unclear. Herein, hot‐electron transfer at Au‐graphene interfaces has been in situ studied using surface‐enhanced Raman spectroscopy (SERS) with atomic layer accuracy. Combining in situ SERS studies with density functional theory calculations, it is proved that hot electrons can be injected from plasmonic Au nanoparticles to graphene and directly penetrate graphene to trigger photocatalytic reactions. With increasing graphene layers, the transportation of hot electrons decays rapidly and would be completely blocked after five layers of graphene. Moreover, the transfer of hot electrons can be modulated by applying an external electric field, and the hot‐electron transfer efficiency under electrochemical conditions is improved by over three times in the presence of a monolayer of graphene. [ABSTRACT FROM AUTHOR]

Our current understanding of the Cambrian carbon cycle mostly comes from geologically rapid carbon isotope excursions (CIEs) of marine carbonate. In addition to carbon cycle indicators, stable carbon isotopes of marine carbonates can be used as stratigraphic correlation tools. Previous studies have recognized 10 CIEs in the Cambrian, but only 3 of them appear to have global significance. This limits the application of CIEs in chronostratigraphic correlation of Cambrian successions with the 10 successive stages. Here, we present a continuous carbon isotope record from a stratigraphically complete Cambrian section at Xiaoerbulak, Aksu region in the Tarim Basin, Xinjiang, China. Its comparison with more than 40 sections across the world shows the carbon isotope record of the Cambrian can be divided into 10 units based on the variation patterns. Each pattern has occurrences in at least two Cambrian tectonic plates, suggesting global significance. A generalized curve consisting of the 10 patterns, Carbon Isotope Pattern Curve (CIPC) has been compiled. Based on the fossil records, the 10 patterns are correlated with the 10 stages of the chronostratigraphic system of the Cambrian. The pattern Angularianis correlated with Fortunian Stage and the lower half of Stage 2, Dampingian with the upper part of Stage 2, Boxian with Stage 3, Rabbitian with Stage 4, Chairian with the lower half of Wuliuan, Zigzagian with the upper Wuliuan Stage, Stickian with the Drumian and Guzhangian stages, Towerian with the Paibian Stage and Lower Jiangshan Stage, Shelfian with Upper Jiangshan Stage and the lower half of Stage 10, and Hillian with the upper half of Stage 10.We suggest that the application of CIPC makes the chronostratigraphy of non‐fossiliferous successions realizable. [ABSTRACT FROM AUTHOR]

The adsorption and electrooxidation of CO molecules at well‐defined Pt(hkl) single‐crystal electrode surfaces is a key step towards addressing catalyst poisoning mechanisms in fuel cells. Herein, we employed in situ electrochemical shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) coupled with theoretical calculation to investigate CO electrooxidation on Pt(hkl) surfaces in acidic solution. We obtained the Raman signal of top‐ and bridge‐site adsorbed CO* molecules on Pt(111) and Pt(100). In contrast, on Pt(110) surfaces only top‐site adsorbed CO* was detected during the entire electrooxidation process. Direct spectroscopic evidence for OH* and COOH* species forming on Pt(100) and Pt(111) surfaces was afforded and confirmed subsequently via isotope substitution experiments and DFT calculations. In summary, the formation and adsorption of OH* and COOH* species plays a vital role in expediting the electrooxidation process, which relates with the pre‐oxidation peak of CO electrooxidation. This work deepens knowledge of the CO electrooxidation process and provides new perspectives for the design of anti‐poisoning and highly effective catalysts. [ABSTRACT FROM AUTHOR]

Pyridine adsorbed on the group-VIIIA transition metal and the coinage metal (IB) electrode surfaces is employed as a model system to explore the metal-dependent nature of surface bonding. The periodic trends of the surface-enhanced Raman spectra are interpreted with the density-functional theory calculation results of bond geometries, bond energies, vibrational frequencies, and the force constants. On the basis of the normal-mode analysis the vibrational frequency shifts of the pyridine internal modes with the total symmetry are discussed in detail from the coupling between these internal modes and the N-M bonds. We show that the spectral properties of the ring breath mode (ν[SUB1]) and the ring asymmetric deformation mode (ν[SUB6a]) are sensitive to the interaction between metal and pyridine molecule. Although the frequency shift of the ν[SUB1] mode is generally regarded as an indicator of the bonding strength, we find that the frequency shift of the ν[SUB6a] mode has a nearly linear dependence on the force constant of the N-M bond; and thus conclude that ν[SUB6a] is a better indicator than ν[SUB1] for the strength of pyridine binding with the metals. [ABSTRACT FROM AUTHOR]