Publications de Majed Chergui | EPFL Graph Search

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Collisional quenching of the NO C2P (v = 0) and D2S+ (v = 0) levels by Ar was studied by means of synchrotron radiation at ACO (Orsay). A depopulation rate of D(O) by Ar was derived; it is in good agreement with previous studies. The C(0) fluorescence shows an anomalous behavior with quencher pressure, which is accounted for by a pressure-induced decrease in the rate of predissocn. [on SciFinder (R)]

We give an overview of our recent work on ultrafast dynamics of chemical (organic dyes, metal-complexes, colloidal quantum dots), and biological (retinal and haem proteins) systems in the liquid phase, studied with a variety of ultrafast optical techniques ...

Fano line shapes are reported in the excitation spectrum of the total fluorescence of NO trapped in Kr matrixes. They result from the homogeneous configuration mixing of the sharp valence vibrational bands B2P(v'=12,15,18)-X2P(v''=0) with the broadened multiphonon Rydberg vibrational bands C2P(v'=0,1,2)-X2P(v''=0). The main features of the spectrum are reproduced by a simulation. [on SciFinder (R)]

Photodissocn. of H2O in Xe matrixes was investigated by excitation in the first continuum (~A1B1) by using dispersed synchrotron radiation. The dissocn. threshold near 6.4 eV corresponds to a barrier of .apprx.1.3 eV due to repulsive H-Xe pair interactions and is attributed to a prompt cage exit of the H atoms. The dissocn. efficiency for cryst. samples does not depend on temp. in the 5-40 range. An increase of the dissocn. efficiency with temp. for non-cryst. samples up to the value of cryst. ones is cause

We describe a simple and low cost design for generating high voltage pulses using commercially available Ruhmkorff's coils. Our application is the biasing of large area photoconductive switches, used for THz generation, operating at kHz repetition rates. T ...

A review. Ultrafast x-ray techniques using diffraction and absorption are discussed with an emphasis on the absorption techniques. Ultrafast x-ray sources and detectors for use in x-ray absorption spectroscopy are also reviewed. [on SciFinder (R)]

The evolution of charge carriers in photoexcited room temperature ZnO nanoparticles in solution is investigated using ultrafast ultraviolet photoluminescence spectroscopy, ultrafast Zn K-edge absorption spectroscopy, and ab initio molecular dynamics (MD) s ...

We show a femtosecond fluorescence upconversion setup with broadband detection to measure time-resolved emission spectra in the 300-550 nm range, upon excitation between 250 and 300 nm, with a time resolution of 100 fs. We present time-resolved fluorescenc ...

A review with 51 refs. of the developments leading to the advent of femtochem. is presented, along with the major achievements that have marked the past fifteen years since the birth of the field. [on SciFinder (R)]

The authors present mol. dynamics simulations of the absorption spectra of the Hg2 mol. in solid Ne, Ar, and Xe. The simulations were performed using classical mol. dynamics (MD) and a diat.-in-mols. (DIM) treatment of the mixing of the different states of Hg2 induced by the environment. The exptl. relative shifts of the X0g+-D1u transition band are qual. well reproduced. The origin of these shifts is identified as the result of two combined factors: the effect of the host onto the Hg-Hg equil. distances an

We present steady-state absorption and emission spectroscopy and femtosecond broadband photoluminescence up-conversion spectroscopy studies of the electronic relaxation of Os(dmbp)(3) (Os1) and Os(bpy)(2)(dpp) (Os2) in ethanol, where dmbp is 4,4'-dimethyl- ...

The bioprotective nature of disaccharides is hypothesized to derive from the modification of the hydrogen bonding network of water which protects biomolecules through lowered water activity at the protein interface. Using ultrafast fluorescence spectroscop ...

We combine time-resolved and temperature-dependent X-ray absorption spectroscopy with state-of-the-art first principles simulations to quantify light- and thermally-induced structural distortions in CsPbBr3 perovskite nanocrystals with atomic-level precisi ...

Multi-dimensional spectroscopies with vacuum ultraviolet (VUV)/x-ray free-electron laser (FEL) sources would open up unique capabilities for dynamic studies of matter at the femtosecond-nanometer time-length scales. Using sequences of ultrafast VUV/x-ray p ...

A review. The cor. version of Figure 5 is given. [on SciFinder (R)]

The comparison between UV transient absorption spectra of wild type bacteriorhodopsin and two tryptophan-mutant proteins gives evidence for the possibility to use tryptophans as ultrafast probes for the photo-induced dipole moment change in retinal proteins.

We present the results of an exptl. and theor. study on the optimum design of shear-force sensors, used in scanning probe microscopes. We have optimized a configuration consisting of a tuning-fork/fiber-tip assembly, achieving quality factors (Q) exceeding ...

A full multiple theor. model (MXAN) is applied to fit picosecond difference x-ray absorption spectra at the Ru L3 edge upon photoexcitation of aq. [RuII(bpy)3]2+. Fitting difference spectra allows an increase in sensitivity, such that slight structural cha ...

Majed Chergui

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Quenching by argon of the nitric oxide Rydberg states lying near the first dissociation limit

Ultrafast (Bio)physical and (Bio)chemical Dynamics

Fano profiles on multiphonon continua in electronic transitions of matrix-isolated nitric oxide

Cage effect on the photodissociation of water in xenon matrixes

High-voltage pulse generator for THz field generation

Ultrafast X-ray Absorption Spectroscopy

Disentangling the evolution of electrons and holes in photoexcited ZnO nanoparticles

Femtosecond fluorescence upconversion setup with broadband detection in the ultraviolet

Femtochemistry

Simulations of the absorption band of the D-state of Hg2 in rare gas matrices

Chemical synthesis and optical properties of size-selected CdSe tetrapod-shaped nanocrystals

Ultrafast Relaxation Dynamics of Osmium-Polypyridine Complexes in Solution

Ultrafast structural dynamics with photons and electrons

Retardation of Bulk Water Dynamics by Disaccharide Osmolytes

Decoupled Structural Responses upon Light and Thermal Functional Activation in CsPbBr3 Perovskites

Nanoscale dynamics by short-wavelength four wave mixing experiments

Medium effects on the spectroscopy and intramolecular energy redistribution of C60 in cryogenic matrices. [Erratum to document cited in CA134:122718]

Tryptophan Residues as Natural Ultrafast Voltmeters in Retinal Proteins

Q-factor optimization of a tuning-fork/fiber sensor for shear-force detection

A Full Multiple Scattering Model for the Analysis of Time-Resolved X-ray Difference Absorption Spectra