Thibault Charpentier

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This article describes the use of an alternative expansion scheme called Floquet-Magnus expansion (FME) to study the dynamics of spin system in solid-state NMR. The main tool used to describe the effect of time-dependent interactions in NMR is the average Hamiltonian theory (AHT). However, some NMR experiments, such as sample rotation and pulse crafting,(More)
In this article, we present an alternative expansion scheme called Floquet-Magnus expansion (FME) used to solve a time-dependent linear differential equation which is a central problem in quantum physics in general and solid-state nuclear magnetic resonance (NMR) in particular. The commonly used methods to treat theoretical problems in solid-state NMR are(More)
In 2001, Mauri and Pickard introduced the gauge including projected augmented wave (GIPAW) method that enabled for the first time the calculation of all-electron NMR parameters in solids, i.e. accounting for periodic boundary conditions. The GIPAW method roots in the plane wave pseudopotential formalism of the density functional theory (DFT), and avoids the(More)
A new approach involving the creation of triple-quantum (TQ) coherences from both TQ and central transitions (CT) is investigated, in order to enhance the efficiency of triple-quantum excitation for I=3/2 nuclei. The RIACT excitation scheme, a soft pi/2 and hard spin-locking pulse, is shown to induce both adiabatic coherence transfer between CT and TQ(More)
A variable B(0) field static (broadline) NMR study of a large suite of niobate materials has enabled the elucidation of high-precision measurement of (93)Nb NMR interaction parameters such as the isotropic chemical shift (delta(iso)), quadrupole coupling constant and asymmetry parameter (C(Q) and eta(Q)), chemical shift span/anisotropy and skew/asymmetry(More)
Porous composite powders, prepared by spray drying of silica and polybromostyrene nanoparticles, were calcined at various temperatures up to 750 degrees C. The structure in these powders are quantitatively investigated by ultra small-angle X-ray scattering, thermogravimetric analysis, and nuclear magnetic resonance measurements. It has been found that the(More)
An integrated computational method which couples classical molecular dynamics simulations with density functional theory calculations is used to simulate the solid-state NMR spectra of amorphous CaSiO(3). Two CaSiO(3) glass models are obtained by shell-model molecular dynamics simulations, successively relaxed at the GGA-PBE level of theory. The calculation(More)
The crystal structure of trisodium uranate, which forms following the interaction between sodium and hyperstoichiometric urania, has been solved for the first time using powder X-ray and neutron diffraction, X-ray absorption near-edge structure spectroscopy, and solid-state (23)Na multiquantum magic angle spinning nuclear magnetic resonance. The compound,(More)
The production of molecular hydrogen in the radiolysis of dried or hydrated nanoporous controlled-pore glasses (CPG) has been carefully studied using 10 MeV electron irradiation at high dose rate. In all cases, the H2 yield increases when the pore size decreases. Moreover, the yields measured in dried materials are two orders of magnitude smaller than those(More)
The purpose of this paper is to investigate the interplay between the chemical shielding anisotropy and quadrupole interaction in MQMAS spectra. 59Co in the compounds Na3Co(NO2)6 and trans-Co[(en2)(NO2)2]NO3 provides model systems for such an investigation. Furthermore, only few results have been reported on the application of the MQMAS method to a spin I =(More)