Plasmons on the edge of MoS2 nanostructures

Using ab initio calculations we predict the existence of one-dimensional (1D), atomically confined plasmons at the edges of a zigzag MoS2 nanoribbon. The strongest plasmon originates from a metallic edge state localized on the sulfur dimers decorating the Mo edge of the ribbon. A detailed analysis of the dielectric function reveals that the observed deviations from the ideal 1D plasmon behavior result from single-particle transitions between the metallic edge state and the valence and conduction bands of the MoS2 sheet. The Mo and S edges of the ribbon are clearly distinguishable in calculated spatially resolved electron energy loss spectrum owing to the different plasmonic properties of the two edges. The edge plasmons could potentially be utilized for tuning the photocatalytic activity of MoS2 nanoparticles

Spatially resolved quantum plasmon modes in metallic nano-films from first principles

Electron energy loss spectroscopy (EELS) can be used to probe plasmon excitations in nanostructured materials with atomic-scale spatial resolution. For structures smaller than a few nanometers quantum effects are expected to be important, limiting the validity of widely used semi-classical response models. Here we present a method to identify and compute spatially resolved plasmon modes from first principles based on a spectral analysis of the dynamical dielectric function. As an example we calculate the plasmon modes of 0.5-4 nm thick Na films and find that they can be classified as (conventional) surface modes, sub-surface modes, and a discrete set of bulk modes resembling standing waves across the film. We find clear effects of both quantum confinement and non-local response. The quantum plasmon modes provide an intuitive picture of collective excitations of confined electron systems and offer a clear interpretation of spatially resolved EELS spectra.Comment: 7 pages, 7 figure

Herregårdshaven på Sønderskov: Havens historie og udvikling set i havekunstnerisk perspektiv

Cand.hort.arch. Kirsten Lund-Andersen gennemgår i denne artikel haven på Sønderskovs historie fra 1400-tallet til i dag i relation til udviklingen i havekunst og -historie

Tjenestehandel med utlandet har økt mye

Ved bruk av materiale fra denne publikasjonen skal Statistisk sentralbyrå oppgis som kilde. Artiklene er tilgjengelig på internett: www.ssb.no/oaTjenestehandelen med utlandet har nesten doblet seg fra 1999 til 2008. Norge tjener mest på eksportinntektene fra sjøfartsnæringen, mens de største utgiftene er knyttet til nordmenns utenlandsreiser. De viktigste handelspartnerne er USA og Storbritannia