An overview on our latest research on UV plasmonics with Rh and Ga metal nanostructures is presented. We will pay attention to their plasmonic performance and UV tunability. For Ga, its polymorphism will be analyzed and for Rh three characteristic geometries will be studied: tripod star, nanocube and tetrahedron. As an alternative to metals, low heat generation materials for bio applications will be analyzed. A numerical analysis of several candidate low loss dielectric materials that show HRI properties in the UV will be presented. In particular, this analysis will focus on the near-field enhancement and scattering directionality above 3 eV.
Plasmonics in the UV-range constitutes a new focus of research due to new challenges arising in fields such as biology, chemistry or spectroscopy. Very recent studies point out gallium and rhodium as good candidates for these purposes because of their low oxidation tendency and at the same time, having a good plasmonic response in the UV and excellent photocatalytic properties. Here we present an overview of the current state of UV-plasmonics with our latest findings in the plasmonic activity of materials like gallium and rhodium.
A new method for calculating the effective dielectric function of a metal-oxide core-shell nanoparticle is presented and compared with existing theories. This new approach can be helpful for predicting the reflectance, transmittance and absorbance spectra of core-shell colloids and nanocomposites which are widely used in photocatalysis or solar energy harvesting.
The use of nanoparticles is spreading in many fields and a frequent way of preparing them is in the form of colloids, whose characterization becomes increasingly important. The spectral reflectance and transmittance curves of such colloids exhibit a strong dependence with the main parameters of the system. By means of a two-flux model we have performed a colorimetric study of gold colloids varying several parameters of the system, including the radius of the particles, the particle number density, the thickness of the system and the refractive index of the surrounding medium. In all cases, trajectories in the L*a*b* color space have been obtained, as well as the evolution of the luminosity, chroma and hue, either for reflectance or transmittance. The observed colors agree well with typical colors found in the literature for colloidal gold, and could allow for a fast assessment of the parameters involved, e.g., the radius of the nanoparticle during the fabrication process.
Plasmonics in the UV-range constitutes a new challenge due to the increasing demand to detect, identify and destroy biological toxins, enhance biological imaging, and characterize semiconductor devices at the nanometer scale. Silver and aluminum have an efficient plasmonic performance in the near UV region, but oxidation reduces its performance in this range. Recent studies point out rhodium as one of the most promising metals for this purpose: it has a good plasmonic response in the UV and, as gold in the visible, it presents a low tendency to oxidation. Moreover, its easy fabrication through chemical means and its potential for photocatalytic applications, makes this material very attractive for building plasmonic tools in the UV. In this work, we will show an overview of our recent collaborative research with rhodium nanocubes (NC) for Plasmonics in the UV.