Publications by Majed Chergui | EPFL Graph Search

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Describing the nanoscale charge carrier transport at surfaces and interfaces is fundamental for designing highperformance optoelectronic devices. To achieve this, we employ time-and angle-resolved photoelectron spectroscopy with ultraviolet pump and extrem ...

The transient electronic and molecular structure arising from photoinduced charge transfer in transition metal complexes is studied by X-ray powder diffraction with a 100 fs temporal and atomic spatial resolution. Crystals containing a dense array of Fe(II ...

The absorption spectrum of H2O in Ne, Ar, Kr, Xe and ice matrixes in the region of the 1st ~A 1B1 continuum is reported. Substantial blue gas-to-matrix shifts are obsd. for the max., which increase with decreasing matrix cage size. The absorption thresholds show much weaker shifts. These features are interpreted in terms of Rydbergization of the (3s/4a1) MO correlated to the ~A state. The photochem. is strongly affected by the environmental effects on the excited state potential surface. An energy threshold

Ultrafast excited-state dynamics of planar Pt, Pd, and Ni dithione-dithiolato complexes were investigated by transient absorption spectroscopy on the femtosecond-picosecond timescale. All studied complexes show a common photobehaviour, although individual ...

Fluorescence spectra from the Rydberg A2S+(v = 0) level of NO trapped in Ne, Ar, Kr, and Xe matrixes were obtained for 2 different sites. The main site is characterized by broad A(0,v'') bands (full width at half max. .simeq. 80 meV), blue gas-to-matrix shifts of the 70-300 meV, and by absorption-emission Stokes shifts of 300 meV in Xe to 800 meV in Ne matrixes. The line shapes and Stokes shifts were treated within a configuration coordinate model by a moment anal. A linear and quadratic coupling was invoke

The far-UV spectral window widely used for the conformational analysis of biomolecules is not easily covered with broad-band lasers. This has made it difficult to use circular dichroism (CD) spectroscopy to directly follow fast structure changes. By combin ...

D. effects and N2 co-doping of Kr solids doped with NO allow continuous tuning of the NO Rydberg state energies in a range 0.35 to 0.68 eV blue of the gas phase. This property is exploited to control the vibronic configuration mixing between the Rydberg C2P and the valence B2P states. The influence on the interference lineshapes resulting from the interaction of discrete valence bands with the broad multiphonon Rydberg bands is discussed in terms of ests. of the Fano indexes. [on SciFinder (R)]

The frequency shifts of the vibrational and rotational transitions of H2, D2, and HD mols. trapped in solid Ar are calcd. at zero temp. and at pressures 0 ? P ? 373 kbar. The pure vibrational and rotational-vibrational transition frequencies are strongly red-shifted in the solid at P = 0, compared to gas-phase values, and the agreement with Raman scattering measurements is generally good. The calcd. pure rotational transitions also show a small red shift at P = 0 in the solid and are in generally good agree

We report on an ultrafast experimental and simulations study of the early relaxation events of photoexcited tryptophan in water. Experimentally, we used fluorescence up-conversion in both polychromatic and single wavelength detection modes in the 300-480 nm range with polarization dependence. We report on the time evolution of the Stokes shift, bandwidth, and anisotropy from tens of femtoseconds to picoseconds. These observables contain signatures of the simultaneous occurrence of intramolecular and solvent

A manifestation of electronic entanglement in core-level spectroscopic measurements of diatomic molecules, reported recently by Schoffler and co-workers, is discussed. The results are reminiscent of Schrodinger's famous Gedanken experiment with the cat (se ...

The ultrafast relaxation of aq. Fe(II)-tris(bipyridine) upon excitation into the singlet metal-to-ligand charge-transfer band (1MLCT) was characterized by femtosecond fluorescence up-conversion and transient absorption (TA) studies. The fluorescence expt. ...

Photochem. reactions and etching efficiencies of polycryst. Cu and GaAs(100) with Cl2 were studied in the spectral range of 105-300 nm by using synchrotron radiation and for Cl2 pressures between 10-6 and 10 mbar. Dissocn. of Cl2 leads in the case of Cu to the formation of CuClx films (typical thickness 104 nm) with an efficiency of .apprx.107 CuClx mols. per generated Cl atom at high Cl2 exposures. For low Cl2 exposures, anisotropic CuClx growth is obsd. in the irradiated area (typical thickness 50 nm) and

Absorption, emission and excitation spectra of NO in N2 and mixed N2/Kr matrixes at various N2 concns. have been recorded by means of tunable synchrotron radiation and ArF laser excitation. The gas-to-matrix shifts, bandwidths and Stokes shifts of the lowest Rydberg level A2S+(v=0) level increase linearly with N2 concn. The blue-shift is attributed to modifications in the bulk properties of the crystals and not to local perturbations. In emission, the fluorescence from B2P(v= 0) and the phosphorescence from

We present steady-state and broadband femtosecond fluorescence spectra of the protonated Schiff base of retinal in various protic and aprotic solvents, as a function of the excitation wavelength. A detailed spectral decomposition of the time-resolved fluor ...

The dynamics of electron bubble formation upon excitation of the A(3ss) Rydberg orbital of NO in solid Ne was studied by conventional spectroscopy and fs pump-probe spectroscopy. The fs pump pulse initiates the formation of a bubble by the expansion of the Ne atoms surrounding the NO impurity, generating a wave packet of intermol. NO-matrix modes. The dynamics exhibits a 1st peak due to the sampling of the initial expansion of the bubble followed by >=1 oscillation of the bubble boundaries, which occurs .ap

Time-resolved fluorescence spectra from the RuN719 dye exhibit very short lifetimes (

Anatase TiO2 is among the most studied materials for light-energy conversion applications, but the nature of its fundamental charge excitations is still unknown. Yet it is crucial to establish whether light absorption creates uncorrelated electron-hole pai ...

The way nuclear motion affects electronic responses has become a very hot topic in materials science. Coherent acoustic phonons can dynamically modify optical, magnetic, and mechanical properties at ultrasonic frequencies, with promising applications as se ...

We review the tremendous advances in ultrafast X-ray science, over the past 15 years, making the best use of new ultrashort X-ray sources including table-top or large-scale facilities. Different complementary X-ray-based techniques, including spectroscopy, ...

The vibrational, rotational, and vibrational-rotational spectra of dil. H2, D2, and HD matrix-isolated in solid Kr and Xe were calcd. at zero temp. and at pressures P = 0-570 kbar. The impurity local mode frequencies were calcd. vs. pressure. The pure vibrational and rotational-vibrational transition frequencies are strongly red shifted in the solid at P = 0 with respect to their gas-phase values, and the pure rotational transitions are weakly red shifted. The agreement with Raman and IR results is generall

Majed Chergui

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Nanoscale-Resolved Surface-to-Bulk Electron Transport in CsPbBr3 Perovskite

Ultrafast inter-ionic charge transfer of transition-metal complexes mapped by femtosecond X-ray powder diffraction

Absorption by dissociative continua in condensed matter: H2O in rare gas and ice matrixes

Ultrafast electronic and vibrational relaxations in mixed-ligand dithione-dithiolato Ni, Pd, and Pt complexes

Rydberg fluorescence of nitric oxide trapped in rare gas matrices

Broad-Band Ultraviolet CD Spectroscopy of Ultrafast Peptide Backbone Conformational Dynamics

Control by density effects of the Rydberg-valence configuration mixing in matrix isolated NO

Frequency shifts of vibrational and rotational states of dilute H2, D2, and HD impurities in solid Ar under pressure

Relaxation Dynamics of Tryptophan in Water: A UV Fluorescence Up-Conversion and Molecular Dynamics Study

The molecular cat

Ultrafast Nonadiabatic Dynamics of [FeII(bpy)3]2+ in Solution

Photochemical etching of Cu and GaAs with Cl2 in the VUV

Spectroscopy of the nitric oxide (NO) molecule in nitrogen and mixed nitrogen/krypton matrixes

Heterogeneity and relaxation dynamics of the photoexcited retianl Schiff base cation in solution

Ultrafast structural dynamics in electronically excited solid neon. I. Real-time probing of the electronic bubble formation

Ultrafast fluorescence studies of dye sensitized solar cells

Strongly bound excitons in anatase TiO2 single crystals and nanoparticles

Phonon-Driven Selective Modulation of Exciton Oscillator Strengths in Anatase TiO2Nanoparticles

Photoinduced Structural Dynamics of Molecular Systems Mapped by Time-Resolved X-ray Methods

Calculation of the spectral transition frequencies of matrix-isolated hydrogen, deuterium, and hydrogen deuteride impurities in solid krypton and xenon under pressure