RESUMEN
Plasmonic response of the metallic structure characterized by sub-nanometer dielectric gaps can be strongly affected by nonlocal or quantum effects. In this paper, we investigate these effects in spherical Na and Au nanomatryoshka structures with sub-nanometer core-shell separation. We use the state-of-the-art quantum hydrodynamic theory (QHT) to study both near-field and far-field optical properties of these systems: results are compared with the classical local response approximation (LRA), Thomas-Fermi hydrodynamic theory (TF-HT), and the reference time-dependent density functional theory (TD-DFT). We find that the results obtained using the QHT method are in a very good agreement with TD-DFT calculations, whereas other LRA and TF-HT significantly overestimate the field-enhancements. Thus, the QHT approach efficiently and accurately describes microscopic details of multiscale plasmonic systems whose sizes are computationally out-of-reach for a TD-DFT approach; here, we report results for Na and Au nanomatryoshka with a diameter of 60 nm.
RESUMEN
Efficient manipulation and long-distance transport of single photons is a key component in nanoscale quantum optics. In this Letter, we study the emission properties of an individual light emitter placed into a nanofiber and coupled to a metallic nanoparticle. We find that plasmonic field enhancement together with nanofiber optical confinement uniquely and synergistically contribute to an overall increase of emission rates as well as quantum yields. We predict a quantum yield enhancement up to a factor of 2.5 with respect to free space for an averaged dipole orientation.
RESUMEN
The new challenging field of fabrication and interconnection of inorganic nanostructures is giving new impetus to the study of solid-solid interfacial properties. In nanocrystals made of two domains of different chemical composition and sharing an interface, the interfacial behavior is indeed critical for the stability of such an interface, and also in determining the mutual interactions of the two domains. Following a recent study by our group on the growth of colloidal nanocrystal heterodimers made of a domain of Au and a domain of CoPt(3), we report here an ab initio density functional theory study of the structural and electronic properties of Au/CoPt(3) interfaces. We have investigated the structure of different bulk CoPt(3) facets and of Au atoms adsorbed on CoPt(3). We calculated CoPt(3) and Au surface energies, Au/CoPt(3) interfacial energies as well as adsorption energies of Au atoms on CoPt(3) and Au, and we can draw some important conclusions about the growth mechanism of gold on the magnetic alloy. Furthermore, we give here a detailed description of surface and interfacial electronic properties, which in turn determine the possibility of tuning conductivity and magnetic properties in the nanostructure.
RESUMEN
Key limitations of the colloidal semiconductor nanorods that have been reported so far are a significant distribution of lengths and diameters as well as the presence of irregular shapes produced by the current synthetic routes and, finally, the poor ability to fabricate large areas of oriented nanorod arrays. Here, we report a seeded-growth approach to the synthesis of asymmetric core-shell CdSe/CdS nanorods with regular shapes and narrow distributions of rod diameters and lengths, the latter being easily tunable up to 150 nm. These rods are highly fluorescent and show linearly polarized emission, whereby the emission energy depends mainly on the core diameter. We demonstrate their lateral alignment as well as their vertical self-alignment on substrates up to areas of several square micrometers.