Publications by Van Thai Pham | EPFL Graph Search

X-ray Absorption Spectroscopy of Ground and Excited Rhenium–Carbonyl–Diimine Complexes: Evidence for a Two-Center Electron Transfer

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

Steady-state and picosecond time-resolved X-ray absorption spectroscopy is used to study the ground and lowest triplet states of ReX(CO)(3)(bpy), X = Etpy (n = 1), Cl, or Br (n = 0). We demonstrate that the transient spectra at both the Re L3- and Br ...

Amer Chemical Soc2013

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

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

Picosecond Time-Resolved X-Ray Emission Spectroscopy: Ultrafast Spin-State Determination in an Iron Complex

Camelia Borca, Van Thai Pham

Wiley-VCH Verlag GmbH2010

Ultrafast Optical and X-ray Absorption Studies of Solvation Dynamics

Van Thai Pham

Solvation dynamics, the process of solvent reorganization upon electronic excitation of a solute, is central to our understanding chemical reactions in liquid phase. Ultrafast optical studies of solvation dynamics have so far been carried out on polyatomic ...

EPFL2010

Time-resolved x-ray absorption spectroscopy: Watching atoms dance

Majed Chergui, Paul Beaud, Wojciech Gawelda, Camelia Borca, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima

The introduction of pump-probe techniques to the field of x-ray absorption spectroscopy (XAS) has allowed the monitoring of both structural and electronic dynamics of disordered systems in the condensed phase with unprecedented accuracy, both in time and i ...

Iop Publishing Ltd, Dirac House, Temple Back, Bristol Bs1 6Be, England2009

Structural analysis of ultrafast extended x-ray absorption fine structure with subpicometer spatial resolution : Application to spin crossover complexes

Majed Chergui, Wojciech Gawelda, Van Thai Pham, Renske Marjan van der Veen

We present a novel analysis of time-resolved extended x-ray absorption fine structure (EXAFS) spectra based on the fitting of the experimental transients obtained from optical pump/x-ray probe experiments. We apply it to the analysis of picosecond EXAFS da ...

2009

Structural determination of photochemically active diplatinum molecule by time-resolved EXAFS spectroscopy

Majed Chergui, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima

Metallica: A large contraction of the PtPt bond in the triplet excited state of the photoreactive [Pt2(P2O5H2)4]4- ion is determined by time-resolved X-ray absorption spectroscopy (see picture). The strengthening of the PtPt interaction is accompanied by a ...

Wiley-VCH Verlag GmbH2009

Femtosecond XANES Study of the Light-Induced Spin Crossover Dynamics in an Iron(II) Complex

Majed Chergui, Paul Beaud, Wojciech Gawelda, Camelia Borca, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen

X-ray absorption spectroscopy is a powerful probe of mol. structure, but it has previously been too slow to track the earliest dynamics after photoexcitation. We investigated the ultrafast formation of the lowest quintet state of aq. iron(II) tris(bipyridi ...

American Association for the Advancement of Science2009

Retrieving photochemically active structures by time-resolved EXAFS spectroscopy

Majed Chergui, Wojciech Gawelda, Camelia Borca, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen, Frederico Alves Lima

Describing the nature and structure of molecular excited states is important in order to understand their chemical reactivity and role as intermediates in photochemical reactions. The recent implementation of x-ray absorption spectroscopy in the ultrafast ...

Iop Publishing Ltd, Dirac House, Temple Back, Bristol Bs1 6Be, England2009

EXAFS structural determination of the Pt2(P2O5H2)44- anion in solution

Majed Chergui, Camelia Borca, Amal El Nahhas, Van Thai Pham, Renske Marjan van der Veen

We present the first structural detn. of the Pt2(P2O5H2)44- anion in soln. by analyzing the extended X-ray absorption fine structure (EXAFS) spectrum of the Pt LIII edge. The data could be fit with a simple model involving single and multiple scattering pa ...

2008

Light-induced spin crossover probed by ultrafast optical and X-ray spectroscopies

Majed Chergui, Wojciech Gawelda, Amal El Nahhas, Andrea Cannizzo, Van Thai Pham, Renske Marjan van der Veen

The photoinduced energy and structural relaxation of aq. iron(II)-tris-bipyridine ([FeII(bpy)3]2+), upon excitation into its singlet metal-to-ligand charge transfer (1MLCT) band, and the population of its short-lived (?0.6 ns) high-spin excited state have ...

2007

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

Majed Chergui, Frank van Mourik, Wojciech Gawelda, Andrea Cannizzo, Van Thai Pham

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. ...

2007

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, Amal El Nahhas, Van Thai Pham

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