Atomically thin transition metal dichalcogenides (TMDCs) are an emerging class of two-dimensional semiconductors. Recently, first opto-electronic devices featuring photodetection as well as electroluminescence have been demonstrated using monolayer TMDCs as active material. However, the light-matter coupling for atomically thin TMDCs is limited by their small absorption length and low photoluminescence quantum yield. Here, we significantly increase the light-matter interaction in monolayer tungsten disulphide (WS 2 ) by coupling the atomically thin semiconductor to a plasmonic nanoantenna. Due to the plasmon resonance of the nanoantenna, strongly enhanced optical near-fields are generated within the WS 2 monolayer. We observe an increase in well as the photoluminescence spectrum are modified by the longitudinal plasmon resonance. The robust hybrid nanoantenna-monolayer system lights the way to efficient photodetectors, solar cells, light emitting and conceptually new valleytronic devices based on two-dimensional materials. Note added: During the review process we became aware of a related study 33 of Ag nanodisc arrays fabricated by electron-beam lithography on monolayer MoS 2 . ASSOCIATED CONTENT Supporting Information. Photoluminescence enhancement of monolayer WS 2 with both excitation and emission polarization matched to the nanoantenna; Absorption spectrum of a WS 2 monolayer; Numerically calculated scattering spectra of the antenna-WS 2 hybrid as a function of the distance between antenna and WS 2 ; Photoluminescence of the WS 2 monolayer without nanoantenna; Photoluminescence intensity depending on excitation power; Details of the simulation technique. This material is available free of charge via the Internet at

Carbon nanotubes produced in arcs have been found to have the form of multiwalled fullerenes, at least over short lengths. Sintering of the tubes to each other is the predominant source of defects that limit the utility of these otherwise perfect fullerene structures. The use of a water-cooled copper cathode minimized such defects, permitting nanotubes longer than 40 micrometers to be attached to macroscopic electrodes and extracted from the bulk deposit. A detailed mechanism that features the high electric field at (and field-emission from) open nanotube tips exposed to the arc plasma, and consequent positive feedback effects from the neutral gas and plasma, is proposed for tube growth in such arcs.

Elemental carbon can be synthesized in a variety of geometrical forms, from three-dimensional extended structures (diamond) to finite molecules (C(60) fullerite). Results are presented here on the magnetic susceptibility of the least well-understood members of this family, nanotubes and C(60) fullerite. (i) Nanotubes represent the cylindrical form of carbon, intermediate between graphite and fullerite. They are found to have significantly larger orientation-averaged susceptibility, on a per carbon basis, than any other form of elemental carbon. This susceptibility implies an average band structure among nanotubes similar to that of graphite. (ii) High-resolution magnetic susceptibility data on C(60) fullerite near the molecular orientational-ordering transition at 259 K show a sharp jump corresponding to 2.5 centimeter-gram-second parts per million per mole of C(60). This jump directly demonstrates the effect of an intermolecular cooperative transition on an intramolecular electronic property, where the susceptibility jump may be ascribed to a change in the shape of the molecule due to lattice forces.

While debonding and subsequent pullout at fiber‐matrix interfaces can improve fracture toughness in ceramic nanocomposites, the magnitudes of these contributions are currently the subject of ongoing debate. To provide quantitative insight into these mechanisms, ceramic matrix nanocomposites were fabricated with a polymer‐derived ceramic matrix, using multiwalled carbon nanotubes (MWCNTs) that exhibit relatively long pullout lengths. In situ micromechanical pullout tests on individual MWCNTs were used to directly measure the strength of the fiber‐matrix interface. Similar pullout lengths were also observed in bulk and thin film composites, where the fracture toughness of the composite films was measured and found to be higher than that of the matrix material. The interfacial properties from the micromechanical test and the pullout lengths from the composite films were then used to estimate the energy release rates for fiber debonding and pullout. Based on the observed MWCNT and composite failure mechanisms, these results are discussed in terms of their relation to previous estimates of toughening in MWCNT‐ceramic nanocomposites, and in terms of design possibilities for further fracture toughness improvements.

Hybridization of plasmonic and excitonic elementary excitations provides an efficient mean of enhancing the optical absorption and emission properties of metal/semiconductor nanostructures and is a key concept for the design of novel efficient optoelectronic devices.Here we investigate the optical properties of 2D MoSe 2 quantum well flakes covered with Au nanoparticles supporting plasmonic resonances. Using spatially resolved confocal spectroscopy, we report the observation of a quenching phenomenon of the Raman scattering and photoluminescence emission of both the MoSe 2 layer and the Au nanoparticles. We found that the quenching of the photoluminescence emission from the Au nanoparticles is partial and measurable unlike the one observed for the Au-covered MoSe 2 layers, which is total. Its dependence on the thickness of the MoSe 2 layer is determined experimentally. Based on electro-dynamics calculations and on the electronic band alignment at the Au/ MoSe 2 interface, the results are interpreted in terms of i) damping of the plasmonic resonance of the Au nanoparticles due to the optical absorption by the MoSe 2 layer ii) a two-pathways charge transfer scheme where the photo-excited electrons leak from the MoSe 2 layer to the Au NPs whereas the photo-excited holes flow in the opposite direction i.e., from the Au NPs to the MoSe 2 layer. The two combined mechanisms account well for the experimental observations and complements the interpretations proposed in the literature for similar metal nanoparticles/transition metal dichalcogenide systems.