Publications de Majed Chergui | EPFL Graph Search

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The structural changes due to formation of electronic bubbles in solid D2 are studied by fluorescence, fluorescence-excitation, and fluorescence-depletion spectroscopy of the lowest Rydberg state, A 2S+(3ss), of the NO impurity. The A X band is strongly blue-shifted (.apprx.0.7 eV) with respect to the gas phase and shows a very broad (full width at half max. .apprx.2000 cm-1) and asym. profile. The shift results from the strong repulsion due to the overlap of the extended Rydberg orbital with the matrix spe

UV-Vis absorption spectra of one-electron reduction products and (MLCT)-M-3 excited states of [(ReCl)-Cl-I(CO)(3)-(N, N)] (N, N = 2,2'-bipyridine, bpy; 1,10-phenanthroline, phen) have been measured by low-temperature spectroelectrochemistry and UV-Vis tran ...

The strength of the electron-phonon coupling parameter and its evolution throughout a solid's phase diagram often determines phenomena such as superconductivity, charge- and spin-density waves. Its experimental determination relies on the ability to distin ...

The ultrafast evolution of the electric field within bacteriorhodopsin was measured by monitoring the absorption changes of a tryptophan residue after excitation of retinal. The Trp absorption decreases within the first 200 femtoseconds and then recovers o ...

In this article we revisit our recent picosecond and femtosecond X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) experiments, probing the ultrafast electronic and geometric evolution of photoexcited haem proteins, namely ferrous N ...

Non-polar solvation dynamics has been investigated using steady-state absorption and emission spectroscopy of the NO A(2)Sigma(+)(3ssigma) Rydberg state in fluid Ar over a wide range of densities spanning the supercritical regime. Equilibrium molecular dyn ...

We report on photoluminescence decay measurements of CdSe nanoparticles over several decades of intensities and times, and as a function of size and temp. A model is proposed for the multi-exponential decay kinetics, and their temp. dependence, in which a ...

Modulations in the time gated ultrafast fluorescence of the protonated Schiff base of retinal in various solvents are reported, which reflect the creation and evolution of vibrational wave packets due to the torsional mode of retinal of frequency .apprx.12 ...

Recent nanomedical applications have again highlighted the significance of silica surface chemistry in solution. Here, we report in situ electronic structure measurements at the silica-aqueous interface as a function of pH for nanoparticles (NPs) of 7, 12, ...

We report on an experimental study with UV and visible ultrafast time-gated emission and transient absorption of the early photodynamics of horse heart Cytochrome c in both ferric and ferrous redox states. A clear separation in time and energy of tryptopha ...

A review. Manipulation of the quantum properties of matter can influence the course of biochem. reactions. Can biol. functions, such as vision or photosynthesis, that are driven by incoherent phenomena have anything to do with quantum mechanics, where the ...

Structural dynamics in semi-quantum and quantum solids (Ne, H2 and D2) is reported, and compared to results in classical solids such as Ar. The structural dynamics is driven by excitation of the lowest Rydberg state of the NO impurity. The resulting charge redistribution induces a local radial deformation of the medium ('bubble' formation) around the impurity. The steady-=state spectroscopic signatures of this process are presented and analyzed in the configuration coordinate model and harmonic approxn. Int

We present temperature-dependent (from room temperature to 80 degrees C) absorption spectra of Au/SiO2 core-shell nanoparticles (NPs) (core diameter: similar to 25 nm) in water in the range from 1.5 to 4.5 eV, which spans the localized surface plasmon reso ...

High-resolution carbon K-edge X-ray photoelectron, X-ray absorption, non-resonant and resonant Auger spectra are presented of gas phase trans-1,3-butadiene alongside a detailed theoretical analysis utilising nuclear ensemble approaches and vibronic models ...

We present a systematic study of the time-integrated fluorescence of native bacteriorhodopsin, as a function of excitation wavelength across the visible absorption band. While the fluorescence max. is unaffected, the spectrum broadens on the high-energy si ...

A comparative study of absorption spectroscopy at 100 K has been performed on three-dimensional crystals of bacteriorhodopsin extd. from a lipidic cubic phase and on native purple membrane. A modified microspectrophotometer has been designed which yields a ...

Environmental effects on electronic states of small mols. in solid rare gases and in liqs. have severe consequences on the photochem.; examples for valence, Rydberg and ionic states as well as the connection to photochem. dry etching are treated. The repulsive interaction of Rydberg states and the solvation of valence and ionic states are related to spectroscopic properties like gas-to-matrix shifts, Stokes shifts and linewidths. Differential shifts of Rydberg and valence states are illustrated for NO in ra

Time-resolved fluorescence spectra for C60 mols. embedded in Ne and Ar matrixes and C70 in Ne matrixes were recorded using a synchroscan streak camera. In the case of C60, the decay times of the S1 state are identical for all fluorescence bands confirming that it is a state of mixed T1g, T2g, and Gg characters. Its lifetime is detd. by the intersystem crossing rate to the triplet manifold which increases in going from Ar to Ne matrixes. This is attributed to a change of the dominant symmetry character of S1

Aqueous ions are central to catalysis and biological function and play an important role in radiation biology as sources of damage-inducing electrons. Detailed knowledge of solute-solvent interactions is therefore crucial. For transition-metal ions, soft X ...

We present a femtosecond broad-band fluorescence up-conversion study of the vibrational relaxation dynamics of two UV chromophores, 2,5-diphenyloxazole (PPO) and para-terphenyl (pTP), pumped with a large excess of vibrational energy (>2000 cm(-1)). The ban ...

Majed Chergui

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Structural dynamics in quantum solids. I. Steady-state spectroscopy of the electronic bubble in solid hydrogens

Origin of electronic absorption spectra of MLCT-excited and one-electron reduced 2,2 '-bipyridine and 1,10-phenanthroline complexes

Temperature-dependent electron-phonon coupling in La_{2−x}Sr_{x}CuO_{4} probed by femtosecond x-ray diffraction

Probing the ultrafast charge translocation of photoexcited retinal in bacteriorhodopsin

Ultrafast X-ray Spectroscopy of Haem Proteins

Ultrafast solvent response upon a change of the solute size in non-polar supercritical fluids

A model for the multi-exponential excited-state decay of CdSe nanocrystals

Vibrational coherences of the protonated Schiff base of all-trans-retinal in solution

Changes in the Silanol Protonation State Measured In Situ at the Silica-Aqueous Interface

Femtosecond UV Studies of the Electronic Relaxation Processes in Cytochrome c

Controlling Biological Functions

Structural dynamics in quantum solids

Disentangling Light- and Temperature-Induced Thermal Effects in Colloidal Au Nanoparticles

Deconvolution of the X-ray absorption spectrum of trans-1,3-butadiene with resonant Auger spectroscopy

On the excitation wavelength dependence of the fluorescence of bacteriorhodopsin

Absorption spectroscopy of three-dimensional bacteriorhodopsin crystals at cryogenic temperatures: effects of altered hydration

Environmental effects on the energetics and photoinduced dynamics of molecular states

Picosecond studies of the intramolecular relaxation processes in isolated C60 and C70 molecules

RETRACTED: Charge transfer to solvent identified using dark channel fluorescence-yield L-edge spectroscopy

A femtosecond fluorescence study of vibrational relaxation and cooling dynamics of UV dyes