Publications by Majed Chergui | EPFL Graph Search

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Controlling the excitonic optical properties of room temperature semiconductors using time-dependent perturbations is key to future optoelectronic applications. The optical Stark effect in bulk and low-dimensional materials has recently shown exciton shift ...

Free-electron lasers and high-harmonic-generation table-top systems are new sources of extreme-ultraviolet to hard X-ray photons, providing ultrashort pulses that are intense, coherent and tunable. They are enabling a broad range of nonlinear optical and s ...

Intersystem crossing (ISC) rates of transition-metal complexes are determined by the complex interplay of a molecule's electronic and structural dynamics. To broaden our understanding of these key factors, we investigate the case of the prototypical d(8)-d ...

Soft-x-ray absorption spectroscopy at the L2,3 edge of the iron center in bovine Hb and hemin under physiol. conditions is reported for the first time. Spectra of the same compds. in solid form are presented for comparison. Striking differences in the elec ...

Anatase TiO2 (a-TiO2) exhibits a strong x-ray absorption linear dichroism in the pre-edge, the XANES and the EXAFS at the titanium K edge. In the pre-edge region, the behavior of the A1-A3 and B peaks originating from the 1s - 3d transitions is due to the ...

We report on deep-to-near-UV transient absorption spectra of core-shell Au/SiO2 and Au/TiO2 nanoparticles (NPs) excited at the surface plasmon resonance of the Au core, and of UV-excited bare anatase TiO2 NPs. The bleaching of the first excitonic transitio ...

The study of biochemical dynamics by ultrafast spectroscopic methods is often restricted by the limited amount of liquid sample available, while the high repetition rate of light sources can induce photodamage. In order to overcome these limitations, we de ...

Absorption, emission and fluorescence-excitation spectra are reported for Hg atoms and Hg2 mols. in Ar, Kr, Xe and N2 matrixes upon excitation by synchrotron radiation in the 260-90 nm range. The fluorescence emitted from all levels issued from the 6s6p configuration (including strongly forbidden 3P0 -> 1S0 and 3P2 -> 1S0 transitions) upon the excitation of autoionized (5d)9(6s)2(np) levels is explained by ionization-recombination processes. Upon excitation of the 1P1 level, the efficiency of the 1P1 -> 3PJ

We present a detailed analysis of the X-ray absorption near-edge structure (XANES) data on the Fe K-edge of CO Myoglobin based on a combined procedure of Molecular Dynamics (MD) calculations and MXAN (Minuit XANes) data analysis that we call D-MXAN. The ab ...

Ultrafast transient absorption spectroscopy of wild-type bacteriorhodopsin (WT bR) and 2 tryptophan mutants (W86F and W182F) is performed with visible light excitation (pump) and UV probe. The aim is to investigate the photoinduced change in the charge dis ...

In haemoglobin the change from the low-spin (LS) hexacoordinated haem to the high spin (HS, S = 2) pentacoordinated domed deoxy-myoglobin (deoxyMb) form upon ligand detachment from the haem and the reverse process upon ligand binding are what ultimately dr ...

We review our recent results on the implementation of picosecond (ps) X-ray absorption spectroscopy to probe the electronic and geometric structure of centres formed by photoexcitation of solar materials such as TiO2 polymorphs and inorganic Cs-based perov ...

Emission, absorption, and excitation spectroscopy was used for a detailed anal. of the optical transitions of Hg2 trapped in cryogenic matrixes. Upon excitation of electronic states correlating to the 3P1 or the 1P1 asymptote, fast nonradiative relaxation leads to emission from the lowest excited A0g+ state in all matrixes, which decays monoexponentially in 1 ms in Ne, 280 ms in Ar, and 12 ms in Xe. In addn., electronically unrelaxed emission of Hg2 is reported in Ne and in Xe matrixes and attributed to the

The development of next-generation perovskite-based optoelectronic devices relies critically on the understanding of the interaction between charge carriers and the polar lattice in out-of-equilibrium conditions. While it has become increasingly evident fo ...

Lead-halide perovskite (LHP) semiconductors are emergent optoelectronic materials with outstanding transport properties which are not yet fully understood. We find signatures of large polaron formation in the electronic structure of the inorganic LHP CsPbB ...

The ultrafast response of cytochrome bc1 is investigated for the first time, via transient absorption spectroscopy. The distinct redox potentials of both c(1)- and b-hemes allow for a clear differentiation of their respective signals. We find that while th ...

The photophysics of ferricyanide in H2O, D2O and ethylene glycol was studied upon excitation of ligand-to-metal charge transfer (LMCT) transitions by combining ultrafast photoelectron spectroscopy (PES) of liquids and transient vibrational spectroscopy. Up ...

Iron-based spin-crossover complexes hold tremendous promise as multifunctional switches in molecular devices. However, real-world technological applications require the excited high-spin state to be kinetically stable-a feature that has been achieved only ...

The dynamics of the ferric CN complexes of the heme proteins Myoglobin and Hb I from the clam Lucina pectinata upon Soret band excitation is monitored using IR and broad band visible pump-probe spectroscopy. The transient response in the UV-vis spectral region does not depend on the heme pocket environment and is very similar to that known for ferrous proteins. The main feature is an instantaneous, broad, short-lived absorption signal that develops into a narrower red-shifted Soret band. Significant transie

Ultrafast excited-state dynamics of Re(L)(CO)(3)(bpy) (L = Cl, Br, n = 0; L = 4-ethyl-pyridine (Etpy), n = 1+; bpy = 2,2'-bipyridine) have been investigated in dimethylformamide (DMF) solution by fluorescence up-conversion (FIUC) and UV - vis transient absorption (TA) with similar to 100 is time,resolution. TA was also measured in the [1-ethyl-3-methyl-imidazolium]BF4 ionic liquid. The complexes show a very broad fluorescence band at 540-550 nm at zero time delay, which decays with 100-140 Is (dependin

Majed Chergui

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Exciton control in a room temperature bulk semiconductor with coherent strain pulses

Progress and prospects in nonlinear extreme-ultraviolet and X-ray optics and spectroscopy

Ultrafast Intersystem Crossing and Structural Dynamics of [Pt(ppy)(mu-(t)Bu(2)pz)](2)

Probing the Electronic Structure of the Hemoglobin Active Center in Physiological Solutions

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

Giant two-photon absorption of anatase TiO2 in Au/TiO2 core-shell nanoparticles

A microfluidic flow-cell for the study of the ultrafast dynamics of biological systems

Spectroscopy and relaxation paths of higher electronic states of mercury atoms and dimers in rare gas matrixes

Dynamic multiple-scattering treatment of X-ray absorption: Parameterization of a new molecular dynamics force field for myoglobin

Functional electric field changes in photoactivated proteins revealed by ultrafast Stark spectroscopy of the Trp residues

Femtosecond X-ray emission study of the spin cross-over dynamics in haem proteins

Time-resolved Element-selective Probing of Charge Carriers in Solar Materials

Spectroscopy and energy relaxation processes of Hg-doped solid neon, argon, and xenon

Quantifying Photoinduced Polaronic Distortions in Inorganic Lead Halide Perovskite Nanocrystals

Evidence of Large Polarons in Photoemission Band Mapping of the Perovskite Semiconductor CsPbBr3

Photo-induced dynamics of the heme centers in cytochrome bc(1)

Charge-transfer and impulsive electronic-to-vibrational energy conversion in ferricyanide: ultrafast photoelectron and transient infrared studies'

Chiral control of spin-crossover dynamics in Fe (II) complexes

Time-resolved visible and infrared study of the Cyano complexes of Myoglobin and of Hemoglobin I from Lucina pectinata

Ultrafast Excited-State Dynamics ef [Re(L)(CO)(3)(bpy)](n) Complexes: Involvement of the Solvent