Publications de Majed Chergui | EPFL Graph Search

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The absorption and emission spectra of the 3P1-1S0 transition of a Hg atom embedded in solid Ar were simulated using the mol. dynamics with quantum transitions algorithm to consider the nonadiabatic transitions between the three adiabatic states. The simulations also take into account the zero-point fluctuations at the exptl. temp. of 4 K using a temp. correction that mimics them. The simulated spectra show fair agreement with the exptl. data for the abs. energies and very good agreement for the absorption-

With its tunable band-gap and its unique optical and electronic properties black phosphorus (BP) opens exciting opportunities for optoelectronic nanotechnology. The band-gap extends from the visible to the mid-infrared spectral range, as a function of samp ...

We describe the facilities for ultraviolet studies in the femtosecond to nanosecond time domain. These facilities consist of: i) a set-up for deep-ultraviolet spectroscopy in the 260–380 nm range in both pump and probe pulses for transient absorption/refle ...

We present the first lasing results of SwissFEL, a hard X-ray free-electron laser (FEL) that recently came into operation at the Paul Scherrer Institute in Switzerland. SwissFEL is a very stable, compact and cost-effective X-ray FEL facility driven by a lo ...

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 ...

We present a systematic study of the ultrafast fluorescence with broadband detection and similar to 110 fs resolution of 5,10,15,20-tetraphenylporphin (TPP) and 2,3,7,8,12,13,17,18-oc-taethylporphin (OEP), with open 3d-shell metals. We also revisit the cas ...

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 ...

Harmonium is a vacuum ultraviolet (VUV) photon source built within the Lausanne Centre for Ultrafast Science (LACUS). Utilising high harmonic generation, photons from 20-110 eV are available to conduct steady-state or ultrafast photoelectron and photoion s ...

Rydberg-Rydberg transitions are induced by absorption from the lowest Rydberg state of NO A 2S+ (3ss) in Ar matrixes, which is excited by an ArF laser at 193.3 nm. The depopulation of the A(v = 0) level to higher Rydberg states is probed by depletion of its fluorescence. Absorption bands are obsd. in the 1.0-2.0 eV region which are attributed to transitions to the 3p, 3d, 4s and 4p members of the Rydberg series. At higher energies, a continuous absorption structure appears. It is attributed to transitions t

Dynamics is discussed of photodissocn. of chlorine in noble gas matrixes. Dissocn. on repulsive surfaces, harpoon reactions and predissocn. of bound states by curve crossing are discussed using the distribution of electronic states of chlorine in the matrix. It is shown that electronic states and particularly Rydberg states of chlorine as well as ionic and charge-transfer states are significantly modified by the matrix environment. 22 Refs. [on SciFinder (R)]

The absorption spectrum of NO in rare gas matrixes was restudied. The valence B2P(v',0) bands which, in the gas phase, show perturbations for v'>=7 due to homogeneous configuration mixing with the Rydberg C2P state, appear unperturbed up to v' = 10 in Xe, 12 in Kr, 14 in Ar, and 19 in Ne matrixes. The perturbations are shifted to higher energies due to the large blue matrix shifts experienced by the Rydberg states. They appear as irregular vibrational spacings, anomalous intensities, and modifications of th

The authors measured the ultrafast response of triangular silver nanoparticles upon femtosecond excitation of their plasmon resonance. After a fast electron relaxation, the signature of a bimodal mech. vibration of the particle is apparent as a spectral mo ...

Understanding the initial steps during ultrafast molecular reactions involving large spin state changes is a vital goal in structural dynamics research. These involve knowledge of the geometric structure of the system. Ultrafast X-ray absorption spectroscopy with 50-100 picosecond time resolution establishes the geometric structure of the short-lived (tau = 0.6 ns) high spin state. Here we focus on time-resolved X-ray absorption studies with 160-200 fs temporal resolution to monitor the structural evolution

Collective modes are responsible for the emergence of novel quantum phases in topological materials. In the quasi-one dimensional (1D) Weyl semimetal (TaSe4)(2)I < i , a charge density wave (CDW) opens band gaps at the Weyl points, thus turning the system ...

The dynamics of non-polar electronic solvation has been studied on a model system consisting of NO-doped solid Ar. Excitation of the lowest Rydberg state A(3ss) of NO leads to formation of an electronic 'bubble', which has been studied by femtosecond pump-probe spectroscopy and classical Mol. Dynamics simulations. The early time behavior of the transients is identified as the inertial component of the medium response. This first response is followed by a recurrent low-frequency oscillatory motion of the cag

Fluorescence of the predissocd. C2P(v = 0) state of NO in the presence of rare gases was investigated by using selective excitation with synchrotron radiation. In the presence of Ar an anomalous pressure behavior was obsd.: at low pressures (0-30 torr), the fluorescence intensity was quenched, but at higher pressures (30-400 torr) an enhancement of intensity was obsd. Furthermore the C(0)-A(3) cascade was induced. Similar results are reported for the other rare gases except for Xe, for which only quenching

Ultrafast optical-domain spectroscopies allow to monitor in real time the motion of nuclei in molecules. Achieving element-selectivity had to await the advent of time resolved X-ray spectroscopy, which is now commonly carried at X-ray free electron lasers. ...

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 ...

The excitation of the Rydberg states is used to study the nonpolar solvation dynamics in supercrit. fluids (SCFs). The system NO in supercrit. Ar serves as the model system. First, the steady-state, absorption and fluorescence spectra of the NO X 2P-A 2S+(3ss) Rydberg transition were recorded in the supercrit. domain of Ar. Then, mol.-dynamics simulations were carried out to explore the details of the structural rearrangements and solvation dynamics upon the excitation of the Rydberg state. The validity of

A model based on fluid dynamics is proposed, which describes the dynamics of a photoinduced spherical deformation in solid hydrogen. The dynamics is driven by femtosecond excitation of the lowest A(3ss) Rydberg state of NO trapped in an H2 crystal, leading to electronic "bubble" formation. The model is based on a continuum approxn. and considers the medium as incompressible. Energy dissipation due to friction is also taken into account. The model provides quant. agreement with exptl. data, suggesting that

Majed Chergui

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Nonadiabatic Dynamics of Excited Hg(3P1) in Ar Matrixes

Photocarrier-induced band-gap renormalization and ultrafast charge dynamics in black phosphorus

The LOUVRE Laboratory: State-of-the-Art Ultrafast Ultraviolet Spectroscopies for Molecular and Materials Science

A compact and cost-effective hard X-ray free-electron laser driven by a high-brightness and low-energy electron beam

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

Ultrafast Broadband Fluorescence Up-conversion Study of the Electronic Relaxation of Metalloporphyrins

Ultrabroadband femtosecond two-dimensional ultraviolet transient absorption

Harmonium: An Ultrafast Vacuum Ultraviolet Facility

Rydberg series in condensed matter: a fluorescence depletion experiment

Cage effect and molecular dynamics of Cl2 in rare gas solids

Rydberg-valence perturbations in matrix-isolated nitric oxide

Time-Resolved Photodynamics of Triangular-Shaped Silver Nanoplates

Femtosecond X-ray Absorption Spectroscopy of a Light-Driven Spin-Crossover Process

Optically induced changes in the band structure of the Weyl charge-density-wave compound (TaSe4)(2)I

Femtosecond dynamics of electronic 'bubbles' in solid argon: viewing the inertial response and the bath coherences

Intensity enhancement of the nitric oxide C2P(v = 0) fluorescence in the presence of rare gases

Element- and enantiomer-selective visualization of molecular motion in real-time

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

Electronic solvation dynamics in non-polar supercritical fluids

Dynamics of Electronic "Bubble" Formation in Solid Hydrogen: A Classical Model Calculation based on Fluid Dynamics