Luminescent amorphous silicon nitride films were fabricated by plasma-enhanced chemical vapor deposition at room temperature followed by thermal oxidation at 100°C. Very bright green emissions were clearly observed with the naked eye in a bright room after the samples had been oxidized. The emission peak is located at 495nm. Fourier-transform infrared absorption spectra and results of depth profiling with x-ray photoelectron spectroscopy indicate that the introduction of oxygen is of a key role in enhancing the photoluminescence intensity of the films. Emission and excitation spectra analyses suggest that the green emission is originated from the radiative recombination in the localized states related to the Si–O bonds.

SERS-active substrate is fabricated by cosputtering Ag and SiO2 onto two-dimensional polystyrene (PS) colloidal particle templates in a magnetron sputtering system. When Ag and SiO2 are cosputtered onto ordered PS templates, the SiO2-isolated Ag island (SiO2-Ag) nanocap arrays with nanogaps and nanoscaled surface roughness form on PS particles, in which "hot spots" are facilely engineered on three-dimensional nanostructures. The surface-enhanced Raman scattering (SERS) activities of the SiO2-Ag nanocap arrays vary nonmonotonically and depend on the film thickness and surface roughness strongly. Under the optimized conditions, the SERS signal intensity of 4-aminothiophenol (PATP) is employed to evaluate the SERS ability (4.41 × 10(5)). The addition of SiO2 not only avoids photobleaching and background fluorescence but also decreases the oxidation rate of Ag and increases the stability of Ag particles. The results demonstrate the potential applications of this technique in reproducible SERS substrate.

Tailored design of photocatalysts with complicated hollow structures is of great importance for promoting environmental remediation. Herein, a monodispersed CuO yolk-shelled structure is synthesized for the first time by simple calcination treatment of a pre-synthesized Cu-EG (ethylene glycol) complex with yolkshelled structure using a simple, environmentally friendly and glycerol-mediated solvothermal method. Ostwald ripening is the main formation mechanism for the yolk-shelled structure. Such CuO yolk-shelled structures show excellent photocatalytic activity, which is 3.65 times faster than that of the commercial CuO powders and is one of the highest reported photocatalytic activities to date in the CuO nanomaterials for the degradation of rhodamine B (RhB) under visible light irradiation. Such a preferable photocatalytic activity is mainly attributed to the unique yolk-shelled structure, which can enable higher multiple light reflections and scattering between the outer spherical shell and the interior core compared with commercial CuO powders, to provide a more efficient way to enhance light-harvesting efficiency.

It is critical to design and synthesize plasmonic nanostructures that can generate very strong and quantitative surface-enhanced Raman scattering (SERS) signals that could be amplified by multiple laser wavelengths to realize the full potential of SERS nanoprobes. Here, we report the synthesis of Au-nanobridged nanogap cucumbers (Au-NNCs) from DNA-modified Au nanorods and comparison of their SERS signals with three different Raman dyes with our recently reported Au-nanobridged nanogap spheres (Au-NNSs). Although the Au-NNSs generate highly stable and reliable signals, these spherical nanogap structures with a smooth surface produce strong SERS signals (SERS enhancement factor at~10 8 ) only with 633 nm excitation laser. The Au-NNCs with a bumpy surface generated up to~3-,~23-, and~130-fold higher SERS signals with 514, 633, and 785 nm excitation laser wavelengths, respectively, compared to the Au-NNSs.Keywords: Surface-enhanced Raman scattering, Nanogap, Core-shell particle, Gold nanorod, Multiple laser wavelength compatibility Plasmonic signal enhancements from gold and silver nanoparticles (AuNPs and AgNPs) have been studied for various applications including surface-enhanced Raman scattering (SERS), 1-7 localized surface plasmon resonance (LSPR), 8,9 colorimetric assay, 10,11 nanoatenna, 12,13 and plasmonic biosensors. 14,15 In the case of SERS, there have been intense research efforts to design and synthesize SERS-active nanostructures that generate stable, reproducible, and strong SERS signals in a controllable fashion for the practical use. [16][17][18][19][20][21] It is now widely known that plasmonic hot spots, formed between plasmonic structures, are responsible for very strong electromagnetic field enhancement that can amplify SERS signals. [22][23][24][25][26] However, controlling and generating these plasmonic nanogaps, especially of~1 nm, in solution is highly challenging, and, therefore, obtaining reliable and quantitative signals from these SERS nanoprobes is not completely addressed yet. Typically, the plasmonic coupling becomes exponentially stronger from~1-nm or smaller plasmonic gap. 16,22,[25][26][27] As a step forward, we recently showed that a high-yield synthesis of Au-nanobridged nanogap particles (Au-NNPs) with~1 nm interior plasmonic gap from DNAmodified AuNPs (DNA-AuNPs) is possible. Although the hollow interior nanogap generates highly uniform and reproducible Au SERS signals from >90% of particles with a narrow distribution of enhancement factors (EFs) from 1.0 × 10 8 to 5.0 × 10 9 , 16 there is still much room for improvement in SERS enhancement, and strong SERS signals from the AuNNPs were obtained only when a 633 nm laser was used as an excitation source. Getting higher SERS intensity and obtaining strong SERS signals from different excitation laser wavelengths are important for more versatile and multiplexed sensing applications of these interior nanogap probes and, in particular, near-infrared (NIR) laser-based in vivo bioimaging and therapeutic applications: radiation in the NIR...