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DOI: 10.1016/j.jnoncrysol.2013.12.006
WoS: 000333778500005
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DOI: 10.1016/j.carbon.2013.10.006
WoS: 000329379300039
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17 Citations
Résumé:

Solutions of alkali metal salts of single-walled carbon nanotubes (SWNTs) show individualization of the nanotubes without sonication-induced shortening. Bundles are fully exfoliated and length measurements show mean length over one micron, a rare case for liquid formulation of SWNTs. These concentrated solutions of individualized nanotubes in organic solvents can be freeze dried leading to ultralight, highly porous, conducting and mechanically stable carbon nanotube cryogels.

Commentaires: 8 pages

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Ref Arxiv: 1311.0165
DOI: 10.1103/PhysRevB.89.155309
WoS: 000334120100002
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11 Citations
Résumé:

We propose the application of nonlinear optics for studies of spatially indirect excitons in coupled quantum wells. We demonstrate, that despite their vanishing oscillator strength, indirect excitons can strongly contribute to the photoinduced reflectivity and Kerr rotation. This phenomenon is governed by the interaction between direct and indirect excitons. Both dark and bright states of indirect excitons can be probed by these nonlinear optical techniques.

Ref HAL: hal-01905144_v1
DOI: 10.1063/1.4865959
WoS: 000332042000013
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17 Citations
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The optical properties of GaN/Al0.15Ga0.85N multiple quantum wells are examined in 8K–300K temperature range. Both polarized CW and time resolved temperature-dependent photoluminescence experiment are performed so that we can deduce the relative contributions of the non-radiative and radiative recombination processes. From the calculation of the proportion of the excitonic population having wave vector in the light cone, we can deduce the variation of the radiative decay time with temperature. We find part of the excitonic population to be localized in concert with the report of Corfdir et al. (Jpn. J. Appl. Phys., Part 2 52, 08JC01 (2013)) in case of a-plane quantum wells. VC 2014 AIP Publishing LLC.

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Ref Arxiv: 1312.4273
DOI: 10.1117/1.JNP.8.083987
WoS: 000336782200002
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10 Citations
Résumé:

A periodic layer of resonant scatterers is considered in the dipolar approximation. An asymptotic expression for the field diffracted is given in terms of an impedance operator. It is shown that surface Bloch modes appear as a collective effect due to the resonances of the scatterers.

Commentaires: 9 pages, 7 figures, extended paper from SPIE Optics+Photonics, Nanostructured Thin Films VI;submitted to Journal of Nanophotonics

Ref HAL: hal-01117164_v1
DOI: 10.1039/C3NJ01349A
WoS: 000331805000033
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62 Citations
Résumé:

We describe a single step preparation of nanostructures of poly(3,4-ethylenedioxythiophene), PEDOT, in the hydrophobic domains of cationic surfactant-based hexagonal mesophases via chemical oxidative polymerization of EDOT monomers using FeCl3 as an oxidizing agent. After polymerization, the hexagonal structure of the mesophases is preserved as demonstrated by polarized light microscopy and X-ray scattering measurements. After extraction from mesophases, the chemical structure of PEDOT is confirmed by Fourier transform infrared spectroscopy. Moreover, PEDOT morphology is checked by transmission and scanning electron microscopies. PEDOT nanostructures with spindle-like or vesicle-like shapes are obtained depending on the experimental conditions. In the original method, high resolution atomic force microscopy, coupled with infrared nanospectroscopy, is used to probe the local chemical composition of PEDOT nanostructures. Finally, the as-prepared PEDOT polymers are characterized by both good thermal stability up to 200 °C and a relatively high conductivity value up to 0.4 S cm−1 as determined by thermogravimetric analysis and four probe measurements respectively.