675 research outputs found
Tuning the Properties of Pd Nanoclusters by Ligand Coatings: Electronic Structure Computations on Phosphine, Thiol, and Mixed PhosphineThiol Ligand Shells
No full textpeer reviewedTuning the properties of Palladium nanoparticles using different protecting ligand shells is an important step toward the application-orientated design of nanoparticles for nano-electronics and catalysis. We present a density functional theoretical characterization of Pd13 and Pd55 metal cores protected by only-thiol, only-phosphine and mixed phosphine-thiol ligand shells. We analyze the ligand contributions to the frontier orbitals and the charge redistribution between the ligand shell and the metal core and show that these properties control the values of the charging energy and the catalytic activity. The charge transfer character of the metal-ligand interaction is influenced by the presence of other ligands in the capping system indicating a cooperative effect in the ligand induced charge redistribution. Because of the interplay between the stabilization of the frontier orbital due to the contribution of the sulfur and the charge donation by the phosphine, the charging energy of the mixed phosphine-thiol protected cluster is larger than that of the only-phosphine and the only-thiol systems. The complementary point of view is adopted for rationalizing the catalytic properties of the clusters by analyzing the effect of the interaction with the metallic core on the properties of the ligand. The impact of solvation on the electronic structure of the ligand capped Pd13 cluster is investigated by including explicitly a layer of water molecules in the model system
Atomistic account of structural and dynamical changes induced by small binders in the double helix of a short DNA
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Interplay of structural and electronic stabilizing factors in neutral and cationic phosphine protected Au13 clusters
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Excitons modeling in CdSe quantum dot dimers and arrays: toward ultrafast coherent information processing
No full textRelative Photoionization Cross Sections of Super-Atom Molecular Orbitals (SAMOs) in C60
No full textPhotoelectron VMI (Velocity Map Imaging) images of C60 using femtosecond laser pulses at different wavelengths.This data is supporting information relating to: Bohl, E., Sokół, K. P., Mignolet, B., Thompson, J. O. F., Johansson, J. O., Remacle, F. & Campbell, E. E. B. Relative Photoionization Cross Sections of Super-Atom Molecular Orbitals (SAMOs) in C60. J. Phys. Chem. A (2015). doi:10.1021/acs.jpca.5b1033
A stabilized finite element method using a discontinuous level set approach for solving two phase incompressible flows
No full textA numerical method for the simulation of three-dimensional incompressible two-phase flows is presented. The proposed algorithm combines an implicit pressure stabilized finite element method for the solution of incompressible two-phase flow problems with a level set method implemented with a quadrature-free discontinuous Galerkin (DG) method [E. Marchandise, J.-F. Remacle, N. Chevaugeon, A quadrature free discontinuous Galerkin method for the level set equation, Journal of Computational Physics 212 (2006) 338-357]. The use of a fast contouring algorithm [N. Chevaugeon, E. Marchandise, C. Geuzaine, J.-F. Remacle, Efficient visualization of high order finite elements, International Journal for Numerical Methods in Engineering] permits us to localize the interface accurately. By doing so, we can compute the discontinuous integrals without neither introducing an interface thickness nor reinitializing the level set. The capability of the resulting algorithm is demonstrated with "large scale" numerical examples (free surface flows: dam break, sloshing) and "small scale" ones (two phase Poiseuille, Rayleigh-Taylor instability). (c) 2006 Elsevier Inc. All rights reserved
Information processing in parallel through directionally resolved molecular polarization components in coherent multidimensional spectroscopy
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Charge Redistribution Effects on the UV-VIS Spectra of Small Ligated Gold Clusters: a Computational Study
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Magnetostructural effects in ligand stabilized Pd13 clusters: a density functional theory study
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Ultrafast fs coherent excitonic dynamics in CdSe quantum dots assemblies addressed and probed by 2D electronic spectroscopy
No full textpeer reviewedWe show in a joint experimental and theoretical study that ultrafast femto-second (fs) electronic coherences can be characterized in semiconducting colloidal quantum dot (QD) assemblies at room temperature. The dynamics of the electronic response of ensembles of CdSe QDs in the solution and of QD dimers in the solid state is probed by a sequence of 3 fs laser pulses as in two-dimensional (2D) electronic spectroscopy. The quantum dynamics is computed using an excitonic model Hamiltonian based on the effective mass approximation. The Hamiltonian includes the Coulomb, spin–orbit, and crystal field interactions that give rise to the fine structure splittings. In the dimers studied, the interdot distance is sufficiently small to allow for an efficient interdot coupling and delocalization of the excitons over the two QDs of the dimer. To account for the inherent few percent size dispersion of colloidal QDs, the optical response is modeled by averaging over
an ensemble of 2000 dimers. The size dispersion is responsible for an inhomogeneous broadening that limits the lifetimes of the excitonic coherences that can be probed to about 150 fs–200 fs. Simulations and experimental measurements in the solid state and in the solution demonstrate that during that time scale, a very rich electronic coherent dynamics takes place that involves several types of intradot and interdot (in the case of dimers) coherences. These electronic coherences exhibit a wide range of beating periods and provide a versatile basis for a quantum information processing device on a fs time scale at room temperature.MONACOM
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