Ga–Mg Core–Shell Nanosystem for a Novel Full Color Plasmonics

How an oxide shell affects the ultraviolet plasmonic behavior of Ga, Mg, and Al nanostructures

“…For aluminum and magnesium the absorption is stronger for the hemispherical case than for the spherical case, probably due to the volume reduction of the metallic core. As a consequence of this, the plasmonic absorption reaches a maximum for these Al and Mg hemispherical nanoparticles for certain values of the [11,13,14], the plasmonic performance is substantially modified by the geometry and the substrate. In general, interactions with the dielectric substrate tend to red-shift the dipolar resonance with respect to the isolated sphere of the same radius [11].…”

“…Comparative study in the far-field: influence of NP shapes Ellipsometry has been used to measured the pseudo-dielectric function of particle-on-substrate nanostructures in order to determine their plasmonic response [12,13]. The measured imaginary part of this pseudo-dielectric function correlates directly with the absorption efficiency that is easier and more accurate to determine numerically.…”

“…3 For hemispherical nanoparticles located on a sapphire substrate, that can be considered experimentally relevant in surface enhancement techniques (bottom row of Figs.3a and 3b) [11,13,14], the plasmonic performance is substantially modified by the geometry and the substrate. In general, interactions with the dielectric substrate tend to red shift the dipolar resonance with respect to the isolated sphere of the same radius [11].…”

“…In this way, with the former we mimic experimental conditions for colloidal chemistry and with the latter, the typical experimental conditions for metallic nanostructures on substrates made of either Ga or Mg [11][12][13][14]. Although the typical Al NP geometry is usually not hemispherical, we use this geometry to facilitate comparison.…”

“…In previous studies, the plasmonic performance of various metals in the UV has been analyzed. Among them, aluminum (Al) [3,[6][7][8][9][10], gallium (Ga) [7,[10][11][12][13], magnesium (Mg) [7,14], and rhodium (Rh) [15][16][17] were identified as particularly promising candidates for UV plasmonics, with properties approaching those of silver (Ag) and gold (Au) widely used for plasmonic applications in the VIS-NIR [10,18]. However, the efficiencies of these metals depends sensitively on the surrounding dielectric environment, and all of them, except Au and Rh, form native oxides that wrap the NP with a shell, whose thickness depends on both the metal and the environmental exposure conditions (temperature and pressure).…”