arXiv subjects

Eric Anglaret

Publications and source records attributed to Eric Anglaret.

8 recordsLinked to original sources

arXiv2016

Surfactant-Free Single Layer Graphene in Water

Dispersing graphite in water to obtain true (single layer) graphene (SLG) in bulk quantity in a liquid has been an unreachable goal for materials scientists in the last decade. Likewise, a diagnostic tool for identifying solubilized SLG in situ has been long awaited. Homogeneous stable dispersions of SLG in water are obtained by mixing graphenide (negatively charged graphene) solutions in tetrahydrofuran (THF) with degassed water and evaporating the organic solvent. In situ Raman spectroscopy of these aqueous dispersions shows all the expected characteristics of single layer graphene, including an intense 2D band of Lorentzian shape and linewidth of 28 cm-1. Transmission electron and atomic force microscopies on deposits confirm SLG character. The resulting additive-free stable water dispersions contain 0.16 mg/mL of SLG.

cond-mat.mtrl-sci↗

arXiv2005

Exfoliation of single-wall carbon nanotubes in aqueous surfactant suspensions: A Raman study

Aqueous suspensions of bundles and individual single-wall carbon nanotubes were prepared with the help of surfactants. We study the changes in the Raman spectra of the suspensions with respect to powders, and of exfoliated tubes with respect to bundles. The radial breathing modes (RBM) upshift in suspensions because of the internal pressure of the liquid. By contrast, no shift is observed in the RBM spectra after exfoliation in the suspensions. However, we demonstrate a selectivity of the exfoliation process for tubes of small diameters.

cond-mat.other↗

arXiv2005

Influence of structure on the optical limiting properties of nanotubes

We investigate the role of carbon nanotubes structure on their optical limiting properties. Samples of different and well-characterized structural features are studied by optical limiting and pump-probe experiments. The influence of the diameter's size on the nano-object is demonstrated. Indeed, both nucleation and growth of gas bubbles are expected to be sensitive to diameter.

cond-mat.other↗

arXiv2005

Nanotube-based systems for broadband optical limiting: towards an operational system

Nanotube-based systems are good candidates for optical limiting against broadband laser pulses. We explore new routes to improve their limiting performances. We show that the diameter of the nanotubes is a key factor to control the performances. On the other hand, we demonstrate that chemically modified nanotubes can be mixed with organic chromophores, leading to high performance composite limiting systems which are particularly efficient in the nanosecond regime due to the cumulative effects of nonlinear scattering and multiphoton absorption.

cond-mat.other↗

arXiv2005

Raman studies of suspensions and solutions of singlewall carbon nanotubes

Raman spectroscopy is used to probe the structure and electronic properties of nanotubes dispersed in a liquid phase. We show that the radial breathing modes are upshifted in suspensions due to the molecular pressure of the solvent. On the other hand, we directly probe charge transfer in solutions of nanotube polyelectrolytes and its reversibility after oxydation in air.

cond-mat.other↗

arXiv2005

Combination of carbon nanotubes and two-photon absorbers for broadband optical limiting

New systems are required for optical limiting against broadband laser pulses. We demonstrate that the association of non-linear scattering from single-wall carbon nanotubes (SWNT) and multiphoton absorption (MPA) from organic chromophores is a promising approach to extend performances of optical limiters over broad spectral and temporal ranges. Such composites display high linear transmission and good neutral colorimetry and are particularly efficient in the nanosecond regime due to cumulative effects.

cond-mat.other↗

arXiv2005

Multi-spectroscopic investigation of the structure of single-wall carbon nanotubes

We present a multispectroscopic structural study of various nanotube samples with different tube diameters. We determine for each sample the mean bundle and tube diameter as well as the tube diameter distribution. The possibility to work on SWNT of various structural characteristics opens new opportunities to correlate the nanotube structure and their physical properties.

cond-mat.other↗

arXiv1995

Small Angle Neutron Scattering of Aerogels: Simulations and Experiments

A numerical simulation of silica aerogels is performed using diffusion-limited cluster-cluster aggregation of spheres inside a cubic box (with periodic boundary conditions). The volume fraction $c$ is taken to be sufficiently large to get a gel structure at the end of the process. In the case of monodisperse spheres, the wavevector dependent scattered intensity $I(q)$ is calculated from the product of the form factor $P(q)$ of a sphere by the structure factor $S(q)$, which is related to the Fourier transform of $g(r)-1$, where $g(r)$ is the pair correlation function between sphere centers. The structure factor $S(q)$ exhibits large-$q$ damped oscillations characteristics of the short range (intra-aggregate) correlations between spheres. These oscillations influence the $I(q)$ curve in the $q$-region between the fractal regime and the Porod regime and quantitative comparisons are made with experiments on colloidal aerogels. Moreover, at small-$q$ values, $S(q)$ goes through a maximum characteristic of large range (inter-aggregate) correlations. Quantitative fits of the maximum in the experimental $I(q)$ curves of base-catalyzed aerogel are presented. In the case of polydisperse spheres, $I(q)$ is calculated directly from a single aggregate simulation. It is shown that increasing polydispersity shifts the location of the cross-over between the fractal and Porod regimes towards low $q$-value.

cond-mat↗