Publications by Majed Chergui | EPFL Graph Search

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Structured progressions, assocd. with the Cl-Rg+ and H-Rg+ charge transfer species, are obsd. for Cl and H atoms isolated in Kr and Xe (Rg) crystals and are assigned as transitions to Rydberg states. The Rydberg levels correspond to delocalized pos. hole states in the rare gas solid (Rg+) orbiting a neg. center (Cl- or H-). For OH in Ar and Kr matrixes, transitions to static charge transfer states are identified. For both of these rather extreme situations, simple model are used successfully to predict the

A review with 30 refs. on some of the authors works on the absorption, excitation and emission spectra of C60 embedded in rare gas matrixes while stressing the role of the environment. The gas phase resonant 2-photon ionization spectrum of C60 is reanalyzed in the light of previous work and the energy of the lowest 3 excited singlet states is detd. with precision. In matrixes, the visible absorption bands are red shifted by an amt. ranging from .apprx.30 cm-1 in Ne matrixes to .apprx.330 cm-1 in Xe matrixes

Hb I (HbI) is an invertebrate monomeric hemeprotein from Lucina pectinata that contains 142 amino acid residues. The HbI heme pocket structural compn. shows an arrangement of phenylalanyl residues (Phe (29), Phe (43) and Phe (68)) that has not been obsd. in the globin families. The photochem. of HbI ligand complexes can yield relevant information about invertebrate globins in terms of ligands rebinding and photophys. processes. We have performed ultrafast measurements to det. the extent of O2 and CO recombi

We report on an element-selective study of the fate of charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr)(3) perovskite nanocrystals in toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing th ...

The structure and defect concentration of colloidal solutions of ZnO nanoparticles, synthesized by a sol gel procedure (SG-NP), as well as commercially available ZnO nanoparticles (SA-NP) are investigated by UV-vis absorption spectroscopy, transmission ele ...

In 2-color optical Kerr effect measurements of water, addnl. signals can occur in the pulse overlap region if the energy difference between pump and probe pulses approaches the Raman resonance of the OH-stretch vibration. These features can be understood b ...

We present a simple electron time of flight spectrometer for time resolved photoelectron spectroscopy of liquid samples using a vacuum ultraviolet (VUV) source produced by high-harmonic generation. The field free spectrometer coupled with the time-preservi ...

The ultrafast nonradiative relaxation processes after photon excitation at 266 nm of Hg2 trapped in a cryogenic Ar matrix were studied by mol. dynamics with quantum transitions. Fourteen electronic surfaces and their corresponding couplings are included in the simulations. The couplings between electronic states are modeled using a DIM treatment of the mixing of the different states of Hg2 induced by the Ar atoms. While the initially excited electronic state is the D1u state, after 10 ps of dynamics most of

Sample prepn. and ligand complex prepn. of Hb I from Lucina pectinata were performed to obtain ultrafast data on ferric HbI-NO, HbI-N3, HbI-H2S and metHbI complexes that suggest a mechanism for the photoinduced redn. of HbI species. Formation of a transient species in the 430 nm region of the ferric derivs., plus the fact that subsequent to the ultrafast measurements a ferrous oxy HbI species was obsd., led to the suggestion that probably a redn. of a ferric to a ferrous deriv. was occurring. Hb I photoredn

A summary of results on the resonance Raman study of I2 in CCl4 and liq. Xe is presented. No discrete fluorescence can be obsd. upon excitation in the bound parts of the B state and instead a resonance Raman spectrum shows up superimposed on a broad fluorescence background. In the time-dependent picture, the resonance Raman spectrum is a signature of the excited state dynamics before the wavepacket decays by dephasing and/or depopulation. The latter is caused by solvent-induced curve crossing events to the

The v' = 0-4 vibrational levels of the b4S- state of NO in Ar and Kr matrtixes were selectively excited in the near-IR by a tunable laser from the metastable a4P state previously populated by an ArF excimer laser. One of the decay channels of the b state is a radiationless transition to low vibrational levels of the B2P state. By monitoring the time- and energy-resolved B2P->X2P fluorescence the energies were detd. of the b, v' levels and the propensity rules of the b, v' -> B, v" transitions. The results

The authors measured the elec. field induced linear dichroism for a wide range of sizes of CdSe nanocrystals. Large ground-state dipole moments were obsd., esp. for the smallest crystals. In these, the authors found a very large anisotropy of the absorptio ...

We combine fluorescence up-conversion and time correlated single photon counting experiments to investigate the 5-benzyl uracil excited state dynamics in methanol from 100 fs up to several ns. This molecule has been proposed as a model for DNA/protein inte ...

It has been recently demonstrated that a pump pulse can generate coherent charge fluctuations in a superconductor through a stimulated Raman process [Mansart, et al., Proc. Natl. Acad. Sci. USA 110, 4539 (2013)]. Here, we present a tutorial review of the b ...

It was recently demonstrated that in ferric myoglobins (Mb) the fluorescence quenching of the photoexcited tryptophan 14 (*Trp(14)) residue is in part due to an electron transfer to the heme porphyrin (porph), turning it to the ferrous state. However, the ...

Static and time-resolved X-ray absorption spectroscopy (XAS) is used to probe the solvent shell structure around iodide and iodine. In particular, we characterize the changes ob served upon electron abstraction of aqueous iodide, which reflects the transit ...

The shifts from gas-phase values of the vibrational and rotational states of H2 impurities substitutionally trapped in solid Ar are calcd. at zero temp. and at pressures 0 < P ? 438 kbar, using the recently developed H2-Ar potential of R. LeRoy and J. Carley (1980). At zero pressure, the calcd. matrix shift in Q1(0) is -21.5 cm-1, in good agreement with expt. Averaging the H2-Ar potential over the center of mass motion of the H2 and Ar atoms is an important correction. The shift in Q1(0) with pressure is ve

Fluorescence (phosphorescence) excitation spectra as well as luminescence spectra and decay times were investigated for NO in N2 and mixed N2/Kr matrixes. All Rydberg states rapidly relax to the ground state in mixed matrixes with the N2 molar fraction exceeding cN2 = 0.35. This dependence on the N2 concn. is attributed to the complete fluorescence quenching of all NO mols. with at least one N2 nearest neighbor. The vibrational levels of the B 2P valence states strongly coupled to the Rydberg state are also

The ultrafast non-radiative relaxation processes between electronic states of Hg2 trapped in a cryogenic argon matrix after photon excitation at 266 nm is studied by mol. dynamics with quantum transitions (MDQT). Population transfer by matrix-induced couplings and vibrational energy relaxation compete on the same time scale during the dynamics. In spite of multiple nonadiabatic crossing events between the 14 different electronic excited states involved in the dynamics, our simulations show that the vibratio

Majed Chergui

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Charge transfer excitations of doped rare gas matrixes

Medium effects on the spectroscopy and intramolecular energy redistribution of C60 in cryogenic matrices

Investigation of the carbon monoxide and oxy hemoglobin I complexes from Lucina pectinata by femtosecond transient absorption

Localized holes and delocalized electrons in photoexcited inorganic perovskites: Watching each atomic actor by picosecond X-ray absorption spectroscopy

Characterizing the Structure and Defect Concentration of ZnO Nanoparticles in a Colloidal Solution

Raman-induced signals in optical Kerr effect measurements of water with elliptically polarized pulses

A simple electron time-of-flight spectrometer for ultrafast vacuum ultraviolet photoelectron spectroscopy of liquid solutions

A Legacy in Chemistry

Vibrational coherence and nonadiabatic dynamics in the condensed phase

Ultrafast studies of ferric complexes of hemoglobin I from Lucina pectinata

Ultrafast intramolecular and caging dynamics in solvents from frequency-domain experiments

Spectra and dynamics of the b4S- state of nitric oxide in argon and krypton matrixes

Linear dichroism of CdSe nanodots: Large anisotropy of the band-gap absorption induced by ground-state dipole moments

A multi-scale time-resolved study of photoactivated dynamics in 5-benzyl uracil, a model for DNA/protein interactions

Investigating pairing interactions with coherent charge fluctuation spectroscopy

Tryptophan-to-heme electron transfer in ferrous myoglobins

Hydrophobicity with atomic resolution: Steady-state and ultrafast X-ray absorption and molecular dynamics studies

Calculated frequency shifts of matrix isolated H2 in solid argon

Electronic relaxation induced by interaction between diatomics in low-temperature matrixes

Vibrational coherence and solvent-induced non-adiabatic couplings