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The surface‐enhanced Raman scattering (SERS) effect was discovered by Richard Van Duyne et al. in 1977. He and coworkers also first utilized an innovative strategy that used SERS to record spectra on such SERS‐inactive substrate surfaces as n‐gallium arsenide (100) surfaces, which were modified by silver nano‐islands. This nanostructure‐enhanced Raman spectroscopy on flat surfaces (NERSoFS) enabled such SERS applications to be expanded to a variety of materials by virtue of SERS‐active nanostructures such as Au or Ag nanoparticles and shell‐isolated nanoparticles. However, most of such systems, although yielding Raman spectra, produce rather low enhancements, especially when used to record spectra on flat surfaces of SERS‐inactive materials. In this work, along with the direction of Van Duyne's borrowing‐SERS strategy and on the basis of the strategy of cascading optical coupling, we consider a theoretically designed optical configuration, based on an attenuated total reflection‐cascading nanostructure to produce enhanced Raman spectroscopy (ATRc‐NERS) on flat surfaces. This system can effectively harvest the incident light, thereby boosting the local optical field of the incident light and also moderately increasing the radiation field of the Raman‐scattered signals. In this way, one can gain 1–2 additional orders of magnitude in Raman enhancement over present NERSoFS systems both on metallic and nonmetallic flat surfaces, which are otherwise SERS‐inactive. This ATRc‐NERS strategy can potentially be used to develop ultrasensitive and versatile tools for surface science, material science, catalysis, electrochemistry, and micro‐electronics and micro‐LED industries. [ABSTRACT FROM AUTHOR]

Surface‐enhanced Raman spectroscopy (SERS) is a powerful surface analytical technique; however, its lack of material and morphological generality is a longtime limitation. The invention of shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) using silica shell‐encapsulated Au nanoparticles (NPs) overcomes these problems. Whereas, it is difficult to obtain a silica shell (less than 1 nm thick) without pinholes for generating extremely high SERS enhancements. Graphene is one of the most promising two‐dimensional materials, which has a single‐atom layer thickness. Moreover, graphene can provide additional SERS chemical enhancement. Herein, we prepared graphene‐coated Au (Au@G) NPs via chemical vapor deposition (CVD). The graphene shell thickness could be controlled from a few layers to multilayers, and the Au@G SERS activities were characterized using mercaptobenzoic acid (MBA) as a probe molecule. Both the pH and high‐temperature stabilities of the Au@G nanoparticles were characterized. Also, Pt‐on‐Au@G satellite structures were developed via a self‐assembly method. Whereby Au@G nanoparticles were coated with Pt nanocatalysts, and this bifunctional SERS substrate could be used to monitor in situ catalytic reaction mechanisms occurring on the Pt surface. [ABSTRACT FROM AUTHOR]

Deep‐learning‐based spectral identification received intensive interests benefiting from the availability of large scale spectral databases. However, for the identification of spectroscopic data such as Raman, the massive experimental data remained challenging, impeding the application of deep neural networks. Here, we describe a new approach with a transfer‐learning model pretrained on a standard Raman spectral database for the identification of Raman spectra data of organic compounds that are not included in the database and with limited data. Our results show that, with transfer learning, classification accuracy improvement of our convolutional neural network reaches 4.1% and that of our fully connected deep neural network reaches 5.0%. By investigating the influence of the source datasets, we find that our transfer learning method is able to incorporate both relevant and seemingly irrelevant source datasets for pretraining, and the relevant source dataset brings better classification accuracy than that of the seemingly irrelevant source dataset. This study demonstrates that the transfer learning technique has great potential in the effective identification of Raman spectra when the number of Raman data is limited. [ABSTRACT FROM AUTHOR]

Electrochemical surface-enhanced Raman spectroscopy has been used to characterize adsorbed species widely but rarely to reaction intermediates on electrodes. In previous studies, the observed surface-enhanced Raman spectroscopy signals were proposed from benzyl species due to the electrochemical reduction of benzyl chloride on silver electrode surfaces. In this work, we reinvestigated the vibrational assignments of benzyl chloride and benzyl radical as the reaction intermediate. On the basis of density functional theory calculations and normal mode analysis, our systematic results provide more reasonable new assignments for both surface species. Further, we investigated adsorption configurations, binding energies, and vibrational frequency shifts of benzyl radical interacting with silver. Our calculated results show that the wagging vibration displays significant vibrational frequency shift, strong coupling with some intramolecular modes in the phenyl ring, and significant changes in intensity of Raman signals. The study also provides absolute Raman intensity in benzyl halides and discusses the enhancement effect mainly due to the binding interaction with respect to free benzyl radical. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Shell-isolated nanoparticles (NPs)-enhanced Raman spectroscopy (SHINERS) can be potentially applied to virtually any substrate type and morphology. How to take a step forward to prepare SHINERS NPs (SHINs) with superior performance is critical for the practical applications of surface-enhanced Raman scattering (SERS) in the breadth and depth. Here, we present a method to obtain 120 nm diameter gold NPs coated with ultrathin silica shells (1-4 nm). The silica shell can be controlled growth through carefully tuning a series of parameters, such as amount of 3-aminopropyl triethoxysilane used, pH, reaction time, and reaction temperature. We compare the enhancement factor of the obtained 120 nm Au with a 4 nm silica shell NPs to the 55 nm Au with a 4 nm silica shell NPs, and the activity of a 120 nm SHINs is nearly 24 times that the 55 nm SHIN from a single particle view. We also compare the enhancement factor of 1 nm silica shell Au@SiO2 NPs with the bare Au NPs. The enhancement factor of 1 nm silica shell Au@SiO2 NPs was found to be about twice that of the bare particles. For a deeper understanding of the source of the giant enhanced electrical field of the 1 nm silica shell Au@SiO2 NPs, we study the plasmonic property of single 1 nm silica shell Au@SiO2 NP on a gold film substrate through correlation of the structure of single NP using SEM with its SPR spectroscopy. We find that the multipolar interaction between the single Au@SiO2 NP and gold film substrate is important for the SERS. Our studies on the performance of 120 nm SHINs and the plasmonic property of these particles can significantly expand the applications of SHINERS technique and improve the understanding of physical nature of SHINs. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]