Wojciech Gawelda

Cette personne n’est plus à l’EPFL

Publications associées (19)

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Structural Determination of a Short-Lived Excited Iron(II) Complex by Picosecond X-Ray Absorption Spectroscopy

Majed Chergui, Wojciech Gawelda, Van Thai Pham

Structural changes of the Fe(II)-tris-bipyridine ([FeII(bpy)3]2+) complex induced by ultrashort pulse excitation and population of its short-lived (?0.6 ns) quintet high spin state were detected by picosecond x-ray absorption spectroscopy. The structural r ...

2007

Capturing transient electronic and molecular structures in liquids by picosecond X-ray absorption spectroscopy

Majed Chergui, Wojciech Gawelda, Van Thai Pham, Amal El Nahhas

We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) spectroscopy with picosecond temporal resoln. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of th ...

2007

Observation of the Solvent Shell Reorganization around Photoexcited Atomic Solutes by Picosecond X-ray Absorption Spectroscopy

Majed Chergui, Wojciech Gawelda, Van Thai Pham

We report on the observation of the solvation shell rearrangement after abstraction of the electron from aq. I- in a laser pump/X-ray probe expt. by recording the X-ray absorption L1- and L3-edge spectra, 50 ps after laser excitation. The L1-edge spectra c ...

2007

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

Majed Chergui, Wojciech Gawelda

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 ...

2006

Time-resolved x-ray absorption spectroscopy of transition metal complexes

Wojciech Gawelda

Electronic structure changes are at the origin of the making, breaking and transformation of bonds. These changes can be visualized by measuring the geometric structure in "real-time" during the course of a chemical reaction, a biological function or a phy ...

EPFL2006

Photexcitation of Aqueous Ruthenium(II)-tris-(2,2'-bipyridine) with High-Intensity Femtosecond Laser Pulses

Majed Chergui, Wojciech Gawelda

The authors report a femtosecond pump-probe study of photochem. of concd. aq. solns. of [Ru(bpy)3]2+, as a function of pump power (up to 2 TW/cm2) at 400 nm excitation. The transient absorption spectra in the 345-660 nm range up to 1 ns time delay enable t ...

2006

A Full Multiple Scattering Model for the Analysis of Time-Resolved X-ray Difference Absorption Spectra

Majed Chergui, Wojciech Gawelda

A full multiple theor. model (MXAN) is applied to fit picosecond difference x-ray absorption spectra at the Ru L3 edge upon photoexcitation of aq. [RuII(bpy)3]2+. Fitting difference spectra allows an increase in sensitivity, such that slight structural cha ...

2006

Broadband femtosecond fluorescence spectroscopy of [Ru(bpy)3]2+

Majed Chergui, Frank van Mourik, Andrea Cannizzo, Wojciech Gawelda, Goran Zgrablic

Femtosecond fluorescence-upconversion studies of aq. [Ru(bpy)3]2+ show a short-lived vibrationally hot emission of the singlet metal-to-ligand charge-transfer state, with an ultrafast intersystem crossing (~ 10 fs) to the triplet state at const. energy (th ...

Wiley-VCH Verlag GmbH2006

Picosecond time-resolved X-ray Absorption Spectroscopy of solvated organometallic complexes

Majed Chergui, Wojciech Gawelda, Melanie Saes

We describe an experimental setup, which measures transient chemical changes of photoexcited solutes in disordered systems via time-resolved X-ray Absorption Spectroscopy (XAS) with picosecond temporal resolution. The setup combines a femtosecond amplified ...

2005

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Observation of the Solvent Shell Reorganization around Photoexcited Atomic Solutes by Picosecond X-ray Absorption Spectroscopy

Majed Chergui, Wojciech Gawelda, Van Thai Pham

2007