Regensburg 2016 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
O: Fachverband Oberflächenphysik
O 59: Photonics and Nanooptics III: Fabrication and Characterization
O 59.1: Vortrag
Mittwoch, 9. März 2016, 15:00–15:15, S051
Magnesium for Active Plasmonics in the Visible Wavelength Range — •Florian Sterl, Nikolai Strohfeldt, Ramon Walter, Andreas Tittl, and Harald Giessen — 4th Physics Institute and Research Center SCoPE, University of Stuttgart, Germany
Investigating new materials plays an important role for advancing the field of nanoplasmonics. Here we fabricate nanodisks from magnesium and demonstrate tuning of their plasmon resonance throughout the whole visible wavelength range by changing the disk diameter. Furthermore, we employ a catalytic palladium cap layer to transform the metallic Mg nanoparticles into dielectric magnesium hydride nanoparticles when exposed to hydrogen gas. We prove that this transition can be reversed in the presence of oxygen. The addition of a titanium buffer layer which separates the Mg and Pd layers from each other significantly enhances the (un)loading dynamics of the particles. During the transition from Mg to MgH2, the plasmon resonance disappears within minutes. When the particles are dehydrogenated, the resonance is fully restored in 10-20 minutes. Large-area samples covered with such nanodisks thus feature an extinction peak that can be repeatedly switched on and off or kept at any intermediate state, which offers new perspectives for active plasmonic metamaterials. Our findings can also contribute to a better understanding of the H2 diffusion dynamics in Mg, which can lead to new insights for H2 storage applications. To this end, we use dark field spectroscopy to observe the scattering spectrum of single Mg nanocrystals during (de)hydrogenation, and make first steps to reproduce our observations in numerical simulations.