Publications de Majed Chergui | EPFL Graph Search

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This perspective presents some recent results concerning ultrafast intramolecular relaxation processes in metal-based molecular complexes. Ultrafast electronic/vibrational relaxation at sub-vibrational time scales, ultrafast intersystem crossing processes ...

Laser generation at 4.96 mm was achieved on the v = 2 -> v = 1 transition of 13C18O dild. in N2 crystals. Conversion efficiencies of 10-20% and stimulated emission cross-sections of ~10-15-10-13 cm2 are reported. [on SciFinder (R)]

We present an Fe K alpha resonant inelastic X-ray scattering (RIXS) and X-ray emission (XES) study of ferrous and ferric hexacyanide dissolved in water and ethylene glycol. We observe that transitions below the absorption edge show that the solvent has a d ...

L2,3 x-ray absorption spectra of aq. [RuII(bpy)3]2+ were recorded in its ground and excited states, 50 ps after short pulse laser excitation. Significant changes in both the XANES (x-ray Near-Edge Absorption Structure) and the EXAFS (Extended x-ray Absorpt ...

We present a compact passively phase-stabilized ultra-broadband 2D Fourier transform setup. A gas (argon)-filled hollow core fiber pumped by an amplified Ti:Al2O3 laser is used as a light source providing spectral range spanning from 420 to 900 nm. Sub-10- ...

The abs. photodissocn. yield of H2O was measured in Ar matrixes at 160 nm. This energy was chosen as it corresponds to the max. of the photodissocn. yield curve. The abs. quantum efficiency is given by h = NOH/n(160 nm), where NOH is the no. of OH mols. produced following the absorption by H2O mols. of n photons at 160 nm. It is, therefore, necessary to know the abs. photon flux as well as the no. of OH mols. in the sample in order to est. h. [on SciFinder (R)]

We present ultrafast pump-probe studies on chem. prepd. CdSe nanocrystals. Upon pulsed optical excitation we find pronounced oscillations, indicating strong coupling to a LO phonon mode. From the polarization dependence of the signal addnl. information abo ...

New time and energy resolved spectra of the L' 2F-X 2P(0,v") bands of NO in Ar and Kr matrixes are reported. The L'(0,v") bands are excited exclusively via the B' 2D valence state and their lifetime is 3000 +- 500 ns in both matrixes. The quantum efficiency for L'(v = 0) emission is estd. as ?0.04. The 2F-2P transition is discussed in terms of a statically induced transition moment involving spin-orbit mixing with B' 2D, but also in terms of nonadiabatic matrix elements due to the coupling to the lattice.

The resonance Raman overtone progressions of I2 in liq. Xe and in CCl4 following excitation in the bound and continuum parts of the B state are discussed and compared with theor. simulations. The intensity distribution of the Raman overtones yields information about the wave packet dynamics in the excited state. The Raman contribution from the bound part can be treated as that of an out going wave packet. This indicates damping within one recurrence due to predissocn. to the repulsive B, a and a' states. Th

Coupling matter excitations to electromagnetic modes inside nano-scale optical resonators leads to the formation of hybrid light-matter states, so-called polaritons, allowing the controlled manipulation of material properties. Here, we investigate the phot ...

The intramol. energy relaxation processes of UV-excited C60 mols. embedded in Ar crystals were studied by picosecond fluorescence studies and femtosecond pump-probe absorption spectroscopy. The various internal energy relaxation steps are clearly identified. The importance of intramol. energy relaxation processes in solid C60 films is underlined. [on SciFinder (R)]

We present ultrafast x-ray absorption studies of photoexcited aqueous iron trisbipyridine with 160 fs and with 70 ps temporal resolution to monitor the structural evolution in this spin-crossover complex.

The advent of x-ray free electron lasers is providing new opportunities for probing the ultrafast excited state dynamics using structurally sensitive techniques. Herein we use excited state wavepacket dynamics of a prototypical Cu(I)-phenanthroline complex ...

Time resolved optical Kerr effect measurements have been used to det. the orientational dynamics of water in the pores of ZrO2 nanostructured films. We demonstrate that local heating effects can safely be ignored and present our results which are manifestl ...

The laser-assisted photoelectric effect from liquid surfaces is reported for the first time. Photoelectrons generated by 35.6 eV radiation from a liquid microjet of water under vacuum are dressed with (h) over bar omega = 1.55 eV laser field. The subsequen ...

We present three different prepn. methods for CdSe colloidal nanoparticles that, when carried out into the Ostwald ripening regime, lead to the development of complex spectral patterns resulting from the overlap of several distinct components corresponding ...

We present a setup which allows the measurement of time-resolved x-ray absorption spectra with picosecond temporal resoln. on liq. samples at the Advanced Light Source at Lawrence Berkeley National Labs. The temporal resoln. is limited by the pulse width of the synchrotron source. We characterize the different sources of noise that limit the expt. and present a single-pulse detection scheme. [on SciFinder (R)]

The bubble build-up following Rydberg state excitation in rare gas matrixes was modeled on a system comprising NO mols. trapped in Ar matrixes. The bubble formation was probed in real time using the time-resolved fluorescence depletion technique. The NO mols. were excited to their A2S+/3ss(v=0) state. Following excitation, the cage reached its equil. configuration on a timescale of 3.8-4.5 ps, depending on the excitation energy. [on SciFinder (R)]

The dynamics of Hb I (HbI) from the clam Lucina pectinata, from wild-type sperm whale (SW) myoglobin, and from the L29F/H64Q/V68F triple mutant of SW, both unligated and bound to hydrogen sulfide (H2S), have been studied in mol. dynamics simulations. Featu ...

The absorption spectrum of H2 mols. in a Ne matrix at 11-12.2 eV due the vibrational levels v' = 0, ..., 7 of the B1Su+ -> X1Sg+ Rydberg transition is reported. [on SciFinder (R)]

Majed Chergui

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On the interplay between charge, spin and structural dynamics in transition metal complexes

A solid state laser at 4.96 mm: carbon monoxide in crystalline nitrogen

X-ray Spectroscopic Study of Solvent Effects on the Ferrous and Ferric Hexacyanide Anions

Electronic and Molecular Structure of Photoexcited [RuII(bpy)3]2+ Probed by Picosecond X-ray Absorption Spectroscopy

Set-up for broadband Fourier-transform multidimensional electronic spectroscopy

Absolute photodissociation quantum yield of water in argon matrixes

Femtosecond polarization relaxation in CdSe nanocrystals

Mechanisms of the L’ 2Φ–X 2Π emission of NO in Ar and Kr matrices

Ultrafast intramolecular and caging dynamics from resonance Raman spectroscopy of I2 in solutions

Energy relaxation pathways between light-matter states revealed by coherent two-dimensional spectroscopy

Picosecond and femtosecond studies of the energy redistribution in matrix-isolated C60 molecules

Femtosecond X-Ray Absorption Spectroscopy of a Photoinduced Spin-Crossover Process

Probing wavepacket dynamics using ultrafast x-ray spectroscopy

Optical Kerr effect studies of the dynamics of confined water

Laser-Assisted Photoelectric Effect from Liquids

Multimodal Distribution of Quantum Confinement in Ripened CdSe Nanocrystals

A setup for ultrafast time-resolved x-ray absorption spectroscopy

"Bubble" dynamics following Rydberg state excitation in rare gas matrixes

Sulfide-binding hemoglobins: effects of mutations on active-site flexibility

Lowest Rydberg state of H2 in a Ne matrix