Among electromagnetic and chemical (CM) contributions to surface-enhanced Raman scattering (SERS), the former is becoming controllable according to the recent progress in nanofabrication of plasmonic metal structures. However, it is still difficult to control the latter effect. Here, the degree of each contribution to SERS signals is examined on well-defined single crystalline facets of gold by using optical field localization within sphere-plane type plasmonic cavities. Crystal face dependent SERS studies of aminobenzenthiol adsorbates clearly show the distinction between CM enhancements on different surfaces, suggesting that the CM-activity of "SERS-hotspots" is closely related to interfacial dipoles formed at metal-molecular junctions.

Surface-enhanced Raman scattering (SERS) spectra are accompanied by broad background emission, which limits improvements in the signal-to-noise ratio. Despite the close correlation between the background generation and the SERS enhancement, the chemical origin of the background emission has remained somewhat mysterious. In this work, SERS spectra of organic monolayers are systematically measured on an atomically defined single crystalline gold surface of various orientations, which specifically define metal-molecule chemical interactions. The use of sphere-plane type plasmonic nanogap structures on a well-defined surface enables us to evaluate the contribution of charge transfer resonances to SERS enhancement. The present results not only reveal that charge transfer resonance at metal-molecule interfaces increases the intensity of plasmon-mediated broadband emission but also provide us a consistent view about electronic structures of metal-molecule interfaces.

In this paper, the local structure of silicon-containing diamond-like carbon (Si-DLC) films is discussed based on the measurement of C K-edge and Si K-edge near-edge x-ray absorption fine structure (NEXAFS) spectra using the synchrotron radiation of 11 types of Si-DLC film fabricated with various synthesis methods and having different elemental compositions. In the C K-edge NEXAFS spectra of the Si-DLC films, the σ* band shrunk and shifted to the lower-energy side, and the π* peak broadened with an increase in the Si content in the Si-DLC films. However, there were no significant changes observed in the Si K-edge NEXAFS spectra with an increase in the Si content. These results indicate that Si–Si bonding is not formed with precedence in Si-DLC film.

Nanostructuring of molecular monolayers is indispensable for integration of multiple functionality within a monolayer. Here, a fabrication method of two-component molecular assembly with nanoscale structures is demonstrated by a combination of reductive desorption of thiol molecules from a Au(111) substrate with local stabilization of the molecular layers using adsorption of Au nanoparticles. The average sizes of the obtained nanoscale molecular features were controlled by changing the size of nanoparticles. A unique functionality of size-controlled nanostructures was presented using redox responses of ferrocene-terminated molecules as a collective response of ferrocene moieties in each nanostructured assembly.

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The effect of soft X-ray irradiation on hydrogenated silicon-containing diamond-like carbon (Si-DLC) films intended for outer space applications was investigated by using synchrotron radiation (SR). We found that the reduction in film thickness was about 60 nm after 1600 mA·h SR exposure, whereas there was little change in their elemental composition. The reduction in volume was attributable to photoetching caused by SR, unlike the desorption of hydrogen in the case of exposure of hydrogenated DLC (H-DLC) film to soft X-rays. The ratio of the sp2 hybridization carbon and sp3 hybridization carbon in the hydrogenated Si-DLC films, sp2/(sp2 + sp3) ratio, increased rapidly from ~0.2 to ~0.5 for SR doses of less than 20 mA·h. SR exposure significantly changed the local structure of carbon atoms near the surface of the hydrogenated Si-DLC film. The rate of volume reduction in the irradiated hydrogenated Si-DLC film was 80 times less than that of the H-DLC film. Doping DLC film with Si thus suppresses the volume reduction caused by exposure to soft X-rays.

Soft X-rays excite the inner shells of materials more efficiently than any other form of light. The investigation of synchrotron radiation (SR) processes using inner-shell excitation requires the beamline to supply a single-color and high-photon-flux light in the soft X-ray region. A new integrated computing multi-layered-mirror (MLM) monochromator was installed at beamline 07A (BL07A) of NewSUBARU, which has a 3 m undulator as a light source for irradiation experiments with high-photon-flux monochromatic light. The MLM monochromator has a high reflectivity index in the soft X-ray region; it eliminates unnecessary harmonic light from the undulator and lowers the temperature of the irradiated sample surfaces. The monochromator can be operated in a high vacuum, and three different mirror pairs are available for different experimental energy ranges; they can be exchanged without exposing the monochromator to the atmosphere. Measurements of the photon current of a photodiode on the sample stage indicated that the photon flux of the monochromatic beam was more than 1014 photons s−1 cm−2 in the energy range 80–400 eV and 1013 photons s−1 cm−2 in the energy range 400–800 eV. Thus, BL07A is capable of performing SR-stimulated process experiments.

12CaO·7Al 2 O 3 (so called C12A7) has been known as mayenite, which is a component of alumina cement. As the crystal is composed of positively charged nano-cages, it can clathrate several different anion species and show different outstanding properties, e.g., high oxidizing ability, high conductivity maintaining its optical transparency, catalytic reactivity for producing ammonia from nitrogen and hydrogen gases, etc., depending on the chemical species clathrated in the cates. In the present study, we focus on the newly obtained C12A7 prepared by solution plasma process and examined its phase stability and crystal structures of the unknown C12A7. TEM, XRD, TG-DTA analyses revealed the unknown C12A7 phase has large lattice parameters and small crystallite size compared to the standard (normal) C12A7 phase and is unstable in O 2 containing atmosphere, whereas is stable in H 2 atmosphere.