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Majed Chergui

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Related publications (250)

Ultrafast photoelectron spectroscopy of photoexcited aqueous ferrioxalate

Majed Chergui, Frank van Mourik, Christopher Alexander Arrell, José Javier Pancracio Ojeda Andara, Luca Longetti, Thomas Roland Barillot, Michele Puppin

The photochemistry of metal-organic compounds in solution is determined by both intra- and inter-molecular relaxation processes after photoexcitation. Understanding its prime mechanisms is crucial to optimise the reactive paths and control their outcome. H ...

2021

Radial Spin Texture of the Weyl Fermions in Chiral Tellurium

Philippe Bugnon, Marco Grioni, Majed Chergui, Oleg Yazyev, Luca Moreschini, Henrik Moodysson Rønnow, Alberto Crepaldi, Simon Karl Moser, Luc Testa, Mauro Fanciulli, Edoardo Martino, Gianmarco Gatti, Daniel Gosalbez Martinez, Silvan Dino Marcos Roth, Serhii Polishchuk, Michele Puppin

Trigonal tellurium, a small-gap semiconductor with pronounced magneto-electric and magneto-optical responses, is among the simplest realizations of a chiral crystal. We have studied by spin- and angle-resolved photoelectron spectroscopy its unconventional ...

AMER PHYSICAL SOC2020

Femtosecond X-ray emission study of the spin cross-over dynamics in haem proteins

Majed Chergui, Giulia Fulvia Mancini, Dominik Kinschel, James Michael Budarz, Boris Sorokin, Oliviero Cannelli, Camila Bacellar Cases Da Silveira, Jérémy Raymond Jean Maurice Rouxel

In haemoglobin the change from the low-spin (LS) hexacoordinated haem to the high spin (HS, S = 2) pentacoordinated domed deoxy-myoglobin (deoxyMb) form upon ligand detachment from the haem and the reverse process upon ligand binding are what ultimately dr ...

Nature Research2020

Energy relaxation pathways between light-matter states revealed by coherent two-dimensional spectroscopy

Majed Chergui, Lars-Hendrik Mewes, Rebecca Ann Ingle

Coupling matter excitations to electromagnetic modes inside nano-scale optical resonators leads to the formation of hybrid light-matter states, so-called polaritons, allowing the controlled manipulation of material properties. Here, we investigate the phot ...

NATURE RESEARCH2020

X-ray absorption linear dichroism at the Ti K-edge of rutile (001) TiO2 single crystal

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

X-ray absorption linear dichroism of rutile TiO2 at the Ti K-edge provides information about the electronic states involved in the pre-edge transitions. Here, linear dichroism with high energy resolution is analyzed in combination with ab initio finite dif ...

INT UNION CRYSTALLOGRAPHY2020

Photoemission from non-polar aromatic molecules in the gas and liquid phase

Majed Chergui, Frank van Mourik, Christopher Alexander Arrell, Lars-Hendrik Mewes, José Javier Pancracio Ojeda Andara, Jakob Grilj, Luca Longetti

The photoelectron spectra of both liquid and gas phase aromatic molecules are reported. The spectra were obtained using a 34.1 eV source produced by high harmonic generation and analysed with the help of high-level ab initio simulations using the reflectio ...

ROYAL SOC CHEMISTRY2020

Evidence of Large Polarons in Photoemission Band Mapping of the Perovskite Semiconductor CsPbBr3

Marco Grioni, Majed Chergui, Alberto Crepaldi, Nicola Marzari, Nicola Colonna, Gianmarco Gatti, Serhii Polishchuk, Thomas Roland Barillot, Michele Puppin, Riccardo De Gennaro, Matthias Wolf

Lead-halide perovskite (LHP) semiconductors are emergent optoelectronic materials with outstanding transport properties which are not yet fully understood. We find signatures of large polaron formation in the electronic structure of the inorganic LHP CsPbB ...

AMER PHYSICAL SOC2020

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

Slow Charge Carrier Relaxation in Gold Nanoparticles

Majed Chergui, Lars-Hendrik Mewes, Thomas Charles Henry Rossi, Lijie Wang, Malte Oppermann, Benjamin Bauer, Davood Zare

We report on ultrafast transient absorption (TA) studies of surface plasmon-excited similar to 25 nm-diameter Au nanoparticles in solution, monitoring the response of the surface plasmon resonance in the visible region (1.7-3.0 eV) and that of the inter- a ...

AMER CHEMICAL SOC2020

Spin cascade and doming in ferric hemes: Femtosecond X-ray absorption and X-ray emission studies

Majed Chergui, Wojciech Gawelda, Christopher Alexander Arrell, Frederico Alves Lima, Giulia Fulvia Mancini, Dominik Kinschel, Oliviero Cannelli, Camila Bacellar Cases Da Silveira, Rebecca Ann Ingle, Jérémy Raymond Jean Maurice Rouxel, Samuel Menzi

The structure-function relationship is at the heart of biology, and major protein deformations are correlated to specific functions. For ferrous heme proteins, doming is associated with the respiratory function in hemoglobin and myoglobins. Cytochrome c (C ...

National Academy of Sciences2020

Mahan excitons in room-temperature methylammonium lead bromide perovskites

László Forró, Majed Chergui, Ana Akrap, Endre Horvath, Tania Palmieri, Edoardo Baldini, Márton Kollár

In a seminal paper, Mahan predicted that excitonic bound states can still exist in a semiconductor at electron-hole densities above the insulator-to-metal Mott transition. However, no clear evidence for this exotic quasiparticle, dubbed Mahan exciton, exis ...

Nature Publishing Group2020

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

Lukas Stingelin, Majed Chergui, Paul Beaud, Thomas Schietinger, Christopher Alexander Arrell, Thomas Schmidt, Leonid Rivkin, Christoph Peter Hauri, Giulia Fulvia Mancini, Rasmus Ischebeck, Eugenio Ferrari, Camila Bacellar Cases Da Silveira, Mike Seidel, Paolo Craievich, Sven Reiche

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 ...

Nature Publishing Group2020

Light-Induced Renormalization of the Dirac Quasiparticles in the Nodal-Line Semimetal ZrSiSe

Helmuth Berger, Philippe Bugnon, Marco Grioni, Majed Chergui, Arnaud Magrez, Luca Moreschini, Alberto Crepaldi, Simon Karl Moser, Gianmarco Gatti, Serhii Polishchuk, Michele Puppin

In nodal-line semimetals, linearly dispersing states form Dirac loops in the reciprocal space with a high degree of electron-hole symmetry and a reduced density of states near the Fermi level. The result is reduced electronic screening and enhanced correla ...

2020

Giant Exciton Mott Density in Anatase TiO2

Majed Chergui, Tania Palmieri, Edoardo Baldini

Elucidating the carrier density at which strongly bound excitons dissociate into a plasma of uncorrelated electron-hole pairs is a central topic in the many-body physics of semiconductors. However, there is a lack of information on the high-density respons ...

2020

Launching Structural Dynamics

Majed Chergui

2020

Ultrafast photoinduced energy and charge transfer

Majed Chergui

After presenting the basic theoretical models of excitation energy transfer and charge transfer, I describe some of the novel experimental methods used to probe them. Finally, I discuss recent results concerning ultrafast energy and charge transfer in biol ...

2019

Exciton dynamics in DNA oligomers studied by broadband deep-UV transient absorption spectroscopy

Majed Chergui, Malte Oppermann, Benjamin Bauer

We report broadband transient absorption measurements of adenine strands in the deep-UV (250-370 nm). By varying the strand length we resolve the interplay between inter-base stacking and exciton formation and dynamics in DNA oligomers. ...

E D P SCIENCES2019

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

Majed Chergui, Olivier Christian Bräm, Andrea Cannizzo

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 ...

AMER CHEMICAL SOC2019

Ultrafast molecular photophysics in the deep-ultraviolet

Majed Chergui

In the landscape of ultrafast spectroscopic tools, the deep- and near-ultraviolet ranges (200–400 nm) have lagged behind due to the lack of tunability of both the pump and the probe pulses in this range. With the advent of novel nonlinear optical methods, ...

2019

Cooling dynamics of electrons in MAPbBr(3) probed in the deep-UV

Majed Chergui, Peter Chen, Thomas Charles Henry Rossi, Lijie Wang, Malte Oppermann, Yu-Hsien Chiang

Transient absorption in the Visible and in the deep-UV is performed on MAPbBr(3) thin films with 3.1 eV pump excitation. The UV probe can access higher order transitions in the material exploring different high-symmetry points of the Brillouin zone. Uncorr ...

E D P SCIENCES2019

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