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Majed Chergui

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Related publications (243)

Page 2 of 13

Ultrafast X-ray Spectroscopy of Haem Proteins

Majed Chergui, Camila Bacellar Cases Da Silveira

In this article we revisit our recent picosecond and femtosecond X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) experiments, probing the ultrafast electronic and geometric evolution of photoexcited haem proteins, namely ferrous N ...

SWISS CHEMICAL SOC2022

Probing the ultrafast charge translocation of photoexcited retinal in bacteriorhodopsin

Majed Chergui, Frank van Mourik, Selma Schenkl

The ultrafast evolution of the electric field within bacteriorhodopsin was measured by monitoring the absorption changes of a tryptophan residue after excitation of retinal. The Trp absorption decreases within the first 200 femtoseconds and then recovers o ...

American Association for the Advancement of Science2005

Ultrafast solvent response upon a change of the solute size in non-polar supercritical fluids

Majed Chergui

Non-polar solvation dynamics has been investigated using steady-state absorption and emission spectroscopy of the NO A(2)Sigma(+)(3ssigma) Rydberg state in fluid Ar over a wide range of densities spanning the supercritical regime. Equilibrium molecular dyn ...

2005

A model for the multi-exponential excited-state decay of CdSe nanocrystals

Majed Chergui, Frank van Mourik, Awos Al Salman

We report on photoluminescence decay measurements of CdSe nanoparticles over several decades of intensities and times, and as a function of size and temp. A model is proposed for the multi-exponential decay kinetics, and their temp. dependence, in which a ...

2009

Vibrational coherences of the protonated Schiff base of all-trans-retinal in solution

Majed Chergui, Stefan Haacke, Goran Zgrablic

Modulations in the time gated ultrafast fluorescence of the protonated Schiff base of retinal in various solvents are reported, which reflect the creation and evolution of vibrational wave packets due to the torsional mode of retinal of frequency .apprx.12 ...

2007

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

Femtosecond UV Studies of the Electronic Relaxation Processes in Cytochrome c

Majed Chergui, Andrea Cannizzo, Olivier Christian Bräm, 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

Controlling Biological Functions

Majed Chergui

A review. Manipulation of the quantum properties of matter can influence the course of biochem. reactions. Can biol. functions, such as vision or photosynthesis, that are driven by incoherent phenomena have anything to do with quantum mechanics, where the ...

American Association for the Advancement of Science2006

Disentangling Light- and Temperature-Induced Thermal Effects in Colloidal Au Nanoparticles

Davood Zare, Majed Chergui, Lijie Wang

We present temperature-dependent (from room temperature to 80 degrees C) absorption spectra of Au/SiO2 core-shell nanoparticles (NPs) (core diameter: similar to 25 nm) in water in the range from 1.5 to 4.5 eV, which spans the localized surface plasmon reso ...

AMER CHEMICAL SOC2022

Deconvolution of the X-ray absorption spectrum of trans-1,3-butadiene with resonant Auger spectroscopy

Majed Chergui, Camila Bacellar Cases Da Silveira, Luca Longetti, Ludmila Maria Diniz Leroy, Thomas Roland Barillot

High-resolution carbon K-edge X-ray photoelectron, X-ray absorption, non-resonant and resonant Auger spectra are presented of gas phase trans-1,3-butadiene alongside a detailed theoretical analysis utilising nuclear ensemble approaches and vibronic models ...

Royal Soc Chemistry2024

On the excitation wavelength dependence of the fluorescence of bacteriorhodopsin

Majed Chergui, Erwin Portuondo Campa, Stefan Haacke, Selma Schenkl, Goran Zgrablic

We present a systematic study of the time-integrated fluorescence of native bacteriorhodopsin, as a function of excitation wavelength across the visible absorption band. While the fluorescence max. is unaffected, the spectrum broadens on the high-energy si ...

Elsevier2007

Absorption spectroscopy of three-dimensional bacteriorhodopsin crystals at cryogenic temperatures: effects of altered hydration

Majed Chergui, Erwin Portuondo Campa, Selma Schenkl

A comparative study of absorption spectroscopy at 100 K has been performed on three-dimensional crystals of bacteriorhodopsin extd. from a lipidic cubic phase and on native purple membrane. A modified microspectrophotometer has been designed which yields a ...

2006

RETRACTED: Charge transfer to solvent identified using dark channel fluorescence-yield L-edge spectroscopy

Majed Chergui, Mercedes Hannelore Rittmann-Frank

Aqueous ions are central to catalysis and biological function and play an important role in radiation biology as sources of damage-inducing electrons. Detailed knowledge of solute-solvent interactions is therefore crucial. For transition-metal ions, soft X ...

2010

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

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

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

Exciton control in a room temperature bulk semiconductor with coherent strain pulses

Majed Chergui, Edoardo Baldini, Oliviero Cannelli, Tania Palmieri

Controlling the excitonic optical properties of room temperature semiconductors using time-dependent perturbations is key to future optoelectronic applications. The optical Stark effect in bulk and low-dimensional materials has recently shown exciton shift ...

American Association for the Advancement of Science (AAAS)2019

Progress and prospects in nonlinear extreme-ultraviolet and X-ray optics and spectroscopy

Majed Chergui

Free-electron lasers and high-harmonic-generation table-top systems are new sources of extreme-ultraviolet to hard X-ray photons, providing ultrashort pulses that are intense, coherent and tunable. They are enabling a broad range of nonlinear optical and s ...

NATURE PORTFOLIO2023

Ultrafast Intersystem Crossing and Structural Dynamics of [Pt(ppy)(mu-(t)Bu(2)pz)](2)

Majed Chergui, Lars-Hendrik Mewes, Rebecca Ann Ingle

Intersystem crossing (ISC) rates of transition-metal complexes are determined by the complex interplay of a molecule's electronic and structural dynamics. To broaden our understanding of these key factors, we investigate the case of the prototypical d(8)-d ...

2020

Probing the Electronic Structure of the Hemoglobin Active Center in Physiological Solutions

Majed Chergui

Soft-x-ray absorption spectroscopy at the L2,3 edge of the iron center in bovine Hb and hemin under physiol. conditions is reported for the first time. Spectra of the same compds. in solid form are presented for comparison. Striking differences in the elec ...

2009

X-ray absorption linear dichroism at the Ti K edge of anatase TiO2 single crystals

Majed Chergui, Giulia Fulvia Mancini, Oliviero Cannelli, Thomas Charles Henry Rossi, Dominik Kinschel, Camila Bacellar Cases Da Silveira, Jérémy Raymond Jean Maurice Rouxel

Anatase TiO2 (a-TiO2) exhibits a strong x-ray absorption linear dichroism in the pre-edge, the XANES and the EXAFS at the titanium K edge. In the pre-edge region, the behavior of the A1-A3 and B peaks originating from the 1s - 3d transitions is due to the ...

2019

A microfluidic flow-cell for the study of the ultrafast dynamics of biological systems

Majed Chergui, Adrien Alexis Paul Chauvet

The study of biochemical dynamics by ultrafast spectroscopic methods is often restricted by the limited amount of liquid sample available, while the high repetition rate of light sources can induce photodamage. In order to overcome these limitations, we de ...

American Institute of Physics2014