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Majed Chergui

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Publications associées (250)

Ultrafast fluorescence studies of dye sensitized solar cells

Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo

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

2012

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

Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo, Thomas James Penfold

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 ...

2012

Ultrabroadband femtosecond two-dimensional ultraviolet transient absorption

Majed Chergui, Frank van Mourik, Cristina Consani, Gerald Auböck

We present a broadband two-dimensional transient absorption setup for the UV around 300 nm with a time resolution of 150 fs. A narrowband, frequency tunable pump pulse and a broadband probe pulse are generated from the output of a noncollinear optical para ...

Optical Society of America2012

The Role of Site-Specific Hydrogen Bonding Interactions in the Solvation Dynamics of N-Acetyltryptophanamide

Majed Chergui, Ahmed Maher Fahmy El-Zohry

Measurements of the ultrafast broadband UV fluorescence of N-acetyltryptophanamide (NATA) provide detailed information on its relaxation patterns in three different solvents: methanol (MeOH), water and acetonitrile (ACN). Several processes leading to excit ...

Amer Chemical Soc2012

Evidence for a Peierls phase-transition in a three-dimensional multiple charge-density waves solid

Majed Chergui, Mathieu Julien Gino Cottet, Fabrizio Carbone, Thomas James Penfold

The effect of dimensionality on materials properties has become strikingly evident with the recent discovery of graphene. Charge ordering phenomena can be induced in one dimension by periodic distortions of a material's crystal structure, termed Peierls or ...

National Academy of Sciences2012

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

Majed Chergui, Christopher Alexander Arrell, Mariateresa Scarongella

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, ...

2012

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

Majed Chergui

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 ...

Royal Soc Chemistry2012

Simulations of X-ray absorption spectra: the effect of the solvent

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Basile Curchod, Thomas James Penfold

We perform quantum mechanics/molecular mechanics molecular dynamics simulations on the Pt-2(P2O5H2)(4) (abbreviated PtPOP) complex; in water, dimethylformamide and ethanol. These are used to calculate the ground state X-ray absorption spectrum of the ...

2012

Femtosecond pump/supercontinuum-probe setup with 20 kHz repetition rate

Majed Chergui, Frank van Mourik, Andrea Cannizzo, Cristina Consani, Gerald Auböck, Roberto Monni

We developed a fast multichannel detection system for pump-probe spectroscopy, capable of detecting single shot super-continuum spectra at the repetition rate (10-50 kHz) of an amplified femtosecond laser system. By tandem pumping the amplifier with three ...

Amer Inst Physics2012

Ultrafast Excited-State Dynamics of Rhenium(I) Photosensitizers [Re(Cl)(CO)(3)(N,N)] and [Re(imidazole)(CO)(3)(N,N)](+): Diimine Effects

Majed Chergui, Olivier Christian Bräm, Amal El Nahhas, Andrea Cannizzo, Cristina Consani

Femto- to picosecond excited-state dynamics of the complexes Re(L)(CO)(3)(N,N) (N,N = bpy, phen, 4,7-dimethyl-phen (dmp); L = Cl, n = 0; L = imidazole, n = 1+) were investigated using fluorescence up-conversion, transient absorption in the 650-285 nm ...

2011

Femtosecond carrier dynamics in bulk graphite and graphene paper

Majed Chergui, Frank van Mourik, Andrea Cannizzo, Gerald Auböck, Fabrizio Carbone

Femtosecond white-light continuum probe transient absorption and reflectivity measurements of bulk graphite and graphene paper are reported. In graphite, the relaxation of photoinduced electron–hole pairs happens through in-plane electron–electron and elec ...

Elsevier2011

Ultrafast X-ray Absorption Studies of the Structural Dynamics of Molecular and Biological Systems in Solution

Majed Chergui, Frank van Mourik, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold, Lotta Susanne Karlsson

We review our recent studies of excited state structures and dynamics of chemical and biological systems with pico- and femtosecond X-ray absorption spectroscopy in the liquid phase. ...

2011

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

Majed Chergui, Amal El Nahhas, Andrea Cannizzo, Cristina Consani

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 ...

Elsevier2011

Femtosecond UV Studies of the Electronic Relaxation Processes in Cytochrome c

Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo, Cristina Consani

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 ...

2011

Ultrafast (Bio)physical and (Bio)chemical Dynamics

Majed Chergui, Olivier Christian Bräm, Frank van Mourik, Amal El Nahhas, Andrea Cannizzo, Ahmad Ajdar Zadeh Oskouei, Renske Marjan van der Veen, Cristina Consani, Gerald Auböck

We give an overview of our recent work on ultrafast dynamics of chemical (organic dyes, metal-complexes, colloidal quantum dots), and biological (retinal and haem proteins) systems in the liquid phase, studied with a variety of ultrafast optical techniques ...

2011

Probing the Transition from Hydrophilic to Hydrophobic Solvation with Atomic Scale Resolution

Majed Chergui, Paul Beaud, Ivano Tavernelli, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima, Thomas James Penfold

Picosecond and femtosecond X-ray absorption spectroscopy is used to probe the changes of the solvent shell structure upon electron abstraction of aqueous iodide using an ultrashort laser pulse. The transient L-1,L-3 edge EXAFS at 50 ps time delay points to ...

2011

A high-repetition rate scheme for synchrotron-based picosecond laser pump/x-ray probe experiments on chemical and biological systems in solution

Majed Chergui, Frank van Mourik, Camelia Borca, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima, Marco Eli Reinhard, Daniel Grollman, Mercedes Hannelore Rittmann-Frank, Lotta Susanne Karlsson

We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection atMHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of ...

American Institute of Physics2011

Multiphoton-Excited Luminescent Lanthanide Bioprobes: Two- and Three-Photon Cross Sections of Dipicolinate Derivatives and Binuclear Helicates

Jean-Claude Bünzli, Majed Chergui, Anne-Sophie Chauvin, Frank van Mourik, Andrea Cannizzo, Bo Song, Gerald Auböck, Svetlana Eliseeva

Multiphoton excited luminescent properties of water-soluble EuIII and TbIII complexes with derivatives of dipicolinic acid functionalized with a polyoxyethylene pendant arm and terminal groups, [Eu(LOMe)3]3-, [Eu(LNH2)3]3-, and [Tb(LOH)3]3-, as well as of ...

2010

Ultrafast Electronic and Structural Phenomena in Graphite and Graphene

Majed Chergui, Fabrizio Carbone

Cambridge, Cambridge University Press2010

Coherent ultrafast torsional motion and isomerization of a biomimetic dipolar photoswitch

Stefan Haacke, Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo

Femtosecond fluorescence up-conversion, UV-Vis and IR transient absorption spectroscopy are used to study the photo-isomerization dynamics of a new type of zwitterionic photoswitch based on a N-alkylated indanylidene pyrroline Schiff base framework (ZW-NAI ...

Royal Society of Chemistry2010

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