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  • NRN136 - Resonant-state expansion of dispersive open optical systems

    05/10/2015

    A resonant-state expansion (RSE) for open optical systems with a general frequency dispersion of the relative permittivity, described by a finite number of simple poles, is presented. As in the non-dispersive case, the RSE of dispersive systems converts Maxwell's wave equation into a linear matrix eigenvalue problem in the basis of unperturbed resonant states, in this way numerically exactly determining all relevant eigenmodes of the optical system. This dispersive RSE is verified by application to the analytically solvable system of a sphere in vacuum, with a dispersion of the dielectric constant described by the Drude and Drude-Lorentz models. We calculate the change of the optical modes when converting the sphere material from gold to non-dispersive silica and back to gold, and evaluate the accuracy using the exact solutions.

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  • NRN093 - Impact of Aggregation on the Photochemistry of Fullerene Films: Correlating Stability to Triplet Exciton Kinetics

    ACS Publications

    • Sensors and Devices, 
    • Modelling, 
    • Knowledge Transfer, 
    • Materials

    The photochemistry and stability of fullerene films is found to be strongly dependent upon film nanomorphology. In particular, PC61BM blend films, dispersed with polystyrene, are found to be more susceptible to photobleaching in air than the more aggregated neat films. This enhanced photobleaching correlated with increased oxygen quenching of PC61BM triplet states and the appearance of a carbonyl FTIR absorption band indicative of fullerene oxidation, suggesting PC61BM photo-oxidation is primarily due to triplet-mediated singlet oxygen generation. PC61BM films were observed to undergo photo-oxidation in air for even modest (≤40 min) irradiation times, degrading electron mobility substantially, indicative of electron trap formation. This conclusion is supported by observation of red shifts in photo- and electro-luminescence with photo-oxidation, shown to be in agreement with time-dependent density functional theory calculations of defect generation. These results provide important implications on the environmental stability of PC61BM-based films and devices.

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  • NRN150 - Defining a performance map of porous carbon sorbents for high-pressure carbon dioxide uptake and carbon dioxide–methane selectivity

    Journals of Chemistry A

    • Materials

    Based upon the data analyzed, a performance map has been defined as a guide to designing/choosing materials for both future studies and large scale fluid bed applications using pelletized materials. For CO2 uptake at 30 bar any material with a surface area >2800 m2 g−1 and a total pore volume >1.35 cm3 g−1 is unlikely to be bettered. Such a material is best prepared by thermal activation between 700–800 °C and will have a carbon content of 80–95 wt% (as determined by XPS). While it has been assumed that the parameters that make a good CO2 adsorbent are the same as those that make a material with high CO2/CH4 selectivity, our results indicate instead that for the best selectivity at 30 bar a surface area >2000 m2 g−1 and a total pore volume >1.0 cm3 g−1 and a carbon content of <90 wt% are necessary.

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  • NRN097 - Continuous and scalable polymer capsule processing for inertial fusion energy target shell fabrication using droplet microfluidics

    Nature

    • Sensors and Devices, 
    • Modelling, 
    • Knowledge Transfer, 
    • Materials

    High specification, polymer capsules, to produce inertial fusion energy targets, were continuously fabricated using surfactant-free, inertial centralisation, and ultrafast polymerisation, in a scalable flow reactor.

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  • NRN082 - Structured Singular Value Analysis for Spintronics Network Information Transfer Control

    IEEE Xplore

    • Sensors and Devices, 
    • Modelling, 
    • Knowledge Transfer

    —Control laws for selective transfer of information encoded in excitations of a quantum network, based on shaping the energy landscape using time-invariant, spatially-varying bias fields,can be successfully designed by using numerical optimization. Such control laws, already departing from classicality by replacing closed-loop asymptotic stability with alternative notions of localization,have the intriguing property that for all practical purposes they achieve the upper bound on the fidelity, yet the (logarithmic)sensitivity of the fidelity to such structured perturbation as spin coupling errors and bias field leakages is nearly vanishing. Here, these differential sensitivity results are extended to large structured variations using µ-design tools to reveal a crossover region in the space of controllers where objectives usually thought to be conflicting are actually concordant.

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