Paul Beaud

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Publications associées (29)

Non-equilibrium phonon dynamics studied by grazing-incidence femtosecond X-ray crystallography

Paul Beaud

The timescales for structural changes in a single crystal of bismuth after excitation with an intense near-infrared laser pulse are studied with femtosecond pump-probe X-ray diffraction. Changes in the intensity and reciprocal-lattice vector of several ref ...

2010

Reply to Comment on Directly observing squeezed phonon states with femtosecond x-ray diffraction

Paul Beaud

American Physical Society2010

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

Ultrafast Structural Phase Transition Driven by Photoinduced Melting of Charge and Orbital Order

Paul Beaud

We use femtosecond x-ray diffraction to probe directly the structural dynamics of a charge ordered and orbitally ordered thin film of La0.42Ca0.58MnO3 initiated by an ultrafast optical pulse. At low excitation fluences we observe the displacive excitation ...

American Physical Society2009

Directly Observing Squeezed Phonon States with Femtosecond X-Ray Diffraction

Paul Beaud

Squeezed states are quantum states of a harmonic oscillator in which the variance of two conjugate variables each oscillate out of phase. Ultrafast optical excitation of crystals can create squeezed phonon states, where the variance of the atomic displacem ...

American Physical Society2009

Local structural changes in excited Ti3+:Al2O3 studied by time-resolved XANES

Paul Beaud

Transient changes in the local structure of optically excited Ti3+ ions in a Al2O3 single crystal are studied by time-resolved x-ray absorption spectroscopy. A model considering coupling of the excited E-2(C-3v) electronic state of the Ti3+ ion to the appr ...

2009

Full Reconstruction of a Crystal Unit Cell Structure during Coherent Femtosecond Motion

Paul Beaud

We present a complete characterization of the unit cell dynamics of a laser-excited tellurium crystal using femtosecond x-ray diffraction. The analysis offers a quantitative measure of the unit cell dynamics without making any assumptions on the symmetry o ...

American Physical Society2009

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

Nanoscale depth-resolved coherent femtosecond motion in laser-excited bismuth

Paul Beaud

We employ grazing-incidence femtosecond x-ray diffraction to characterize the coherent, femtosecond laser-induced lattice motion of a bismuth crystal as a function of depth from the surface with a temporal resolution of 193 +/- 8 fs. The data show direct c ...

American Physical Society2008

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