Plasmon excitations in metallic nanostructures

A new hyperspectral imaging technique and apparatus for imaging plasmon excitations and cathodoluminescence in nanostructures with nanoscale resolution have been developed. The apparatus, based on a scanning electron microscope synchronized with a multi-channel spectrum analyzer, allows for collection and detection of optical electron-induced emission from a sample in two configurations (high efficiency and high angular resolution modes) and in the wavelength region from 350 to 1150 nm with 0.8 nm spectral resolution and high quantum efficiency.Using this instrument it was demonstrated that the injection of a beam of free electrons into an unstructured metal surface creates a highly localized nanoscale source of SPPs. It was shown that on a gold surface a 50 keV electron beam of 10 μA current creates a 10 nW source of plasmons with the spectrum spreading from 350 to 1150 nm. The plasmons were detected by controlled decoupling into light with a grating at a distance from the excitation point. The 30 nm delocalization of the plasmon source at the grating was demonstrated and decay lengths of SPPs were measured.The hyperspectral imaging technique was used to study plasmon emission, induced by an electron beam excitation on gold monocrystal decahedronshaped nanoparticles and dimers consisting of such nanoparticles. It was shown that in 100 nm gold decahedron-shaped nanoparticles electron-induced plasmon emission is excited in the spectral range from 350 to 850 nm. The dependence of spatial and spectral structure of dimer plasmon emission on wavelength and separation between the nanoparticles within the dimer was studied. The excitation of hybridized mode on a dimer with a 50 nm gap between the particles was detected at wavelength 600 nm. It was demonstrated that the electromagnetic field structure near a plasmonic nanoparticle forms a vortex. It was shown that the power-flow lines of linear polarized monochromatic light interacting with a metal lambda/20 nanoparticle, in the proximity of its plasmon resonance, form whirlpool-like nanoscale optical vortices (optical whirlpools). Both spherical and spheroidal particles were studied using analytical Mie theory and the Finite Element method. One of two types of vortices, inward or outward, was observed depending on the sign of frequency detuning between the external field and plasmon resonance of the nanoparticle

Generation of surface plasmons by electron beam excitation

We report on the first demonstration of excitation of propagating surface plasmon polaritons (SPPs) by injection of a beam of free electrons on an unstructured metal interface, providing a highly localized and intense source of plasmon waves. The plasmons were detected by a grating-assisted decoupling into light at a set of distances from the excitation point. This technique allows the high-resolution mapping of plasmon and photon emission from metal nanostructures

SentiCircles: A Platform for Contextual and Conceptual Sentiment Analysis

Sentiment analysis over social streams offers governments and organisations a fast and effective way to monitor the publics’ feelings towards policies, brands, business, etc. In this paper we present SentiCircles, a platform that captures feedback from social media conversations and applies contextual and conceptual sentiment analysis models to extract and summarise sentiment from these conversations. It provides a novel sentiment navigation design where contextual sentiment is captured and presented at term/entity level, enabling a better alignment of positive and negative sentiment to the nature of the public debate

Achieving accurate FTIR measurements on high performance bandpass filters

The sources of ordinate error in FTIR spectrometers are reviewed with reference to measuring small out-of-band features in the spectra of bandpass filters. Procedures for identifying instrumental artefacts are described. It is shown that features well below 0.01%T can be measured reliably

Electron beam excitation of plasmonic modes in gold dimers

We report on the first realization of hyperspectral imaging for visualization and excitation of plasmon modes in dimers of 100 nm gold decahedra by a scanning electron beam

SERSCIS-Ont: A Formal Metrics Model for Adaptive Service Oriented Frameworks

In the Future Internet, programs will run on a dynamically changing collection of services, entailing the consumption of a more complex set of resources including financial resources. The von Neumann model offers no useful abstractions for such resources, even with refinements to address parallel and distributed computing devices. In this paper we detail the specification for a post-von Neumann model of metrics where program performance and resource consumption can be quantified and encoding of the behaviour of processes that use these resources is possible. Our approach takes a balanced view between service provider and service consumer requirements, supporting service management and protection as well as non-functional specifications for service discovery and composition

Hyperspectral imaging of plasmonic excitations induced by an electron beam

We report on the first realization of a hyperspectral imaging technique of surface plasmon polaritons using a scanning electron beam. The technique provides for plasmon imaging and information on decay lengths with nanometer resolution

Linking quality of service and experience in distributed multimedia systems using PROV semantics

Experimenters creating innovative applications that combine diverse distributed multimedia services with rich end user applications require enhanced insight into the relationships between the perceived quality of experience (QoE) and provided quality of service (QoS). We have implemented software which not only captures QoE and QoS measurements but, using a provenance ontology, also records the interactions between end users, the content, applications and the services. The data exploration interface provided allows an experimenter, working with participants in real-world situations, to understand the detail of the participants’ usage and experience of the system and the system performance factors contributing to their quality of experience

Women as paid organizers and propagandists for the British Labour Party between the wars

This article contributes to recent debates about the complicated ways in which women involved in the interwar British Labour Party negotiated their political identities through an examination of the activities and aims of a neglected group, the paid women organizers. It suggests that although they accepted the importance of women's work within the home, the organizers did not see women's lives as confined by domesticity. Instead, they argued that women in the home had the potential for collective political action. The article looks at the campaign for pit head baths to highlight the attempt by the organizers to develop a politics around issues such as dirt that concerned women in their daily lives. It was difficult to persuade the Labour Party to take these questions seriously, and the organizers experienced constraints as well as opportunities that came from their paid role, but it is argued here that they did carve a career that was woman-focused and sought to give women in the home a voice