Although gold nanoparticles stabilized by organic thiols are the building blocks in a wide range of applications, the role of the ligands on the plasmon resonance of the metal core has been mostly ignored until now. Herein, a methodology based on the combination of spectroscopic ellipsometry and UV-vis spectroscopy is applied to extract dielectric functions of the different components. It is shown that aromatic thiols allow a significant charge transfer at the hybrid interface with the s and d bands of the gold core that yields "giant" red shifts of the plasmon band, up to 40 nm for spherical particles in the size range of 3-5 nm. These results suggest that hybrid nanoplasmonic devices may be designed through the suitable choice of metal core and organic components for optimized charge exchange.

A new, simple bi-phasic dip-coating method is developed. This method is considered as a great improvement of the technique for research, development and production, since expensive, rare, harmful, or time-evolving solutions can now be easily deposited on large surfaces and on a single side from very little amounts of solution.

International audienceThis article presents the evolution of the photo-luminescence (PL) of silicon quantum dots (QDs) with an average diameter of 5–6 nm dispersed in alcohol under different conditions. Two samples were considered after alcohol dispersion: freshly synthesized (kept in air for 2 days) QDs which do not exhibit luminescence and air-aged (kept in air for 2 years) QDs exhibiting red-IR luminescence. Experiments performed with addition of a small volume of water, followed by heating for different times showed that the oxidation occurs gradually until transforming totally the initial material in SiO2. The oxidation process does not enable the appearance of PL from the Si core for dispersed non-aged powders, while it results in a blue shift of the PL maximum intensity for the aged ones. The results obtained after UV illumination clearly indicate an effect of the UV irradiation on the luminescence of QDs dispersed in aqueous environment, and the treatments with acidic water lead to the conclusion of a possible enhancement of the PL by hydrogen passivation of the non-radiative defects. This result should be taken into account for post-production treatments and applications, more particularly, considering a controlled and safe use of luminescent Si QDs

Within the list of the different technologies developed to provide “clean” alternative energy in the future, Concentrated Solar Power systems (CSP), transforming sunlight radiation into thermal or electrical power, are serious candidates. However, some of the main critical issues to the success of the industrial CSP are the solar-to-thermal and the thermal-to-electrical conversion efficiencies, which require robust absorbing systems, capable of withstanding high operating temperatures for decades. In the present communication, we report the preparation of such performing coatings through accurate control of synthesis and processing, achieved using a simple and scalable bottom-up approach. These new systems are composed of highly controlled nanocrystalline RuO2/SiO2 composite designed such that the device stays highly stable in air at 873 K for more than 1000 h while possessing a high solar selectivity (α > 0.94, and ε@873 K <0.28), making them one of the most promising advancements for CSP technologies.

Silicon wafers are decorated with photoamine generator 4,5-dimethoxy-2-nitrobenzyl 3-(triethoxysilyl)propyl carbamate. UV-irradiation in the presence of benzyl-l-glutamate N-carboxyanhydride is carried out, resulting in the release of the surface-bound primary amines, making them viable N-carboxyanhydride (NCA) polymerization initiators. Successful polypeptide grafting is confirmed by water contact angle measurements as well as by ellipsometry, revealing a poly(benzyl-l-glutamate) (PBLG) layer of ≈3 nm. X-ray photoelectron spectroscopy confirms the presence of amide groups in the grafted PBLG while time-of-flight secondary ion mass spectroscopy provides additional evidence for the presence of PBLG on the surface. Evaluation of negative control samples confirms successful UV surface grafting. The approach is thus established as a viable general method for light exposure directable polypeptide functionalization of silicon surfaces.

The synthesis of silicon quantum dots is performed in the [3-5 nm]

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