Publications de Thomas James Penfold

Revealing hole trapping in zinc oxide nanoparticles by time-resolved X-ray spectroscopy

Majed Chergui, Wojciech Gawelda, Thomas James Penfold, Jochen Rittmann, Fabio Giacomo Santomauro

Nature Research2018

Revealing hole trapping in zinc oxide nanoparticles by time-resolved X-ray spectroscopy

Majed Chergui, Wojciech Gawelda, Thomas James Penfold, Jochen Rittmann, Fabio Giacomo Santomauro

AMER CHEMICAL SOC2018

Photoaquation Mechanism of Hexacyanoferrate(II) Ions: Ultrafast 2D UV and Transient Visible and IR Spectroscopies

Majed Chergui, Gerald Auböck, Marco Eli Reinhard, Thomas James Penfold, Raphaël Horváth

Ferrous iron(II) hexacyanide in aqueous solutions is known to undergo photoionization and photoaquation reactions depending on the excitation wavelength. To investigate this wavelength dependence, we implemented ultrafast two-dimensional UV transient absor ...

American Chemical Society2017

Photophysics of a copper phenanthroline elucidated by trajectory and wavepacket-based quantum dynamics: a synergetic approach

Majed Chergui, Ivano Tavernelli, Thomas James Penfold, Gloria Capano

On-the-fly excited state molecular dynamics is a valuable method for studying non-equilibrium processes in excited states and is beginning to emerge as a mature approach much like its ground state counterparts. In contrast to quantum wavepacket dynamics me ...

Royal Society of Chemistry2017

Identifying the major intermediate species by combining time-resolved X-ray solution scattering and X-ray absorption spectroscopy

Thomas James Penfold

Identifying the intermediate species along a reaction pathway is a first step towards a complete understanding of the reaction mechanism, but often this task is not trivial. There has been a strong on-going debate: which of the three intermediates, the CHI ...

Royal Soc Chemistry2015

NO binding kinetics in myoglobin investigated by picosecond Fe K-edge absorption spectroscopy

Majed Chergui, Camelia Borca, Frederico Alves Lima, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold, Jochen Rittmann, Mahsa Silatani

Diatomic ligands in hemoproteins and the way they bind to the active center are central to the protein's function. Using picosecond Fe K-edge X-ray absorption spectroscopy, we probe the NO-heme recombination kinetics with direct sensitivity to the Fe-NO bi ...

National Academy of Sciences2015

Local Control Theory in Trajectory Surface Hopping Dynamics Applied to the Excited-State Proton Transfer of 4-Hydroxyacridine

Ursula Röthlisberger, Ivano Tavernelli, Basile Curchod, Thomas James Penfold

The application of local control theory combined with nonadiabatic ab initio molecular dynamics to study the photoinduced intramolecular proton transfer reaction in 4-hydroxyacridine was investigated. All calculations were performed within the framework of ...

2015

A Theoretical Rationalisation of the Emission Properties of Prototypical Cu(I)-Phenanthroline Complexes

Ursula Röthlisberger, Ivano Tavernelli, Thomas James Penfold, Gloria Capano

The excited state properties of transition metal complexes have become a central focus of research owing to a wide range of possible applications that seek to exploit their luminescence properties. Herein, we use density functional theory (DFT), time-depen ...

2015

Probing wavepacket dynamics using ultrafast x-ray spectroscopy

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Thomas James Penfold, Gloria Capano

The advent of x-ray free electron lasers is providing new opportunities for probing the ultrafast excited state dynamics using structurally sensitive techniques. Herein we use excited state wavepacket dynamics of a prototypical Cu(I)-phenanthroline complex ...

IOP Publishing2015

Characterizing the Structure and Defect Concentration of ZnO Nanoparticles in a Colloidal Solution

Majed Chergui, Camelia Borca, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold, Jochen Rittmann, Thomas Charles Henry Rossi

The structure and defect concentration of colloidal solutions of ZnO nanoparticles, synthesized by a sol gel procedure (SG-NP), as well as commercially available ZnO nanoparticles (SA-NP) are investigated by UV-vis absorption spectroscopy, transmission ele ...

Amer Chemical Soc2014

Recent experimental and theoretical developments in time-resolved X-ray spectroscopies

Majed Chergui, Thomas James Penfold

Capturing the evolving geometric and electronic structure in the course of a chemical reaction or biological process is the principal aim of time-resolved X-ray spectroscopies. Recent technological and methodological improvements, such as high repetition r ...

Elsevier2014

Mapping of the Photoinduced Electron Traps in TiO2 by Picosecond X-ray Absorption Spectroscopy

Majed Chergui, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold, Jochen Rittmann

Titanium dioxide (TiO2) is the most popular material for applications in solar-energy conversion and photocatalysis, both of which rely on the creation, transport, and trapping of charges (holes and electrons). The nature and lifetime of electron traps at ...

Wiley-Blackwell2014

Probing the dynamics of plasmon-excited hexanethiol-capped gold nanoparticles by picosecond X-ray absorption spectroscopy

Majed Chergui, Thomas James Penfold, Jochen Rittmann

Picosecond X-ray absorption spectroscopy (XAS) is used to investigate the electronic and structural dynamics initiated by plasmon excitation of 1.8 nm diameter Au nanoparticles (NPs) functionalised with 1-hexanethiol. We show that 100 ps after photoexcitat ...

Royal Society of Chemistry2014

A Quantum Dynamics Study of the Ultrafast Relaxation in a Prototypical Cu(I)-Phenanthroline

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Thomas James Penfold, Gloria Capano

The ultrafast nonadiabatic dynamics of a prototypical Cu(I)phenanthroline complex, Cu(dmp)(2) (dmp = 2,9-dimethyl-1,10-phenanthroline), initiated after photoexcitation into the optically bright metal-to-ligand charge-transfer (MLCT) state (S-3) is inv ...

2014

Probing the electronic and geometric structure of ferric and ferrous myoglobins in physiological solutions by Fe K-edge absorption spectroscopy

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Frederico Alves Lima, Marco Eli Reinhard, Thomas James Penfold

We present an iron K-edge X-ray absorption study of carboxymyoglobin (MbCO), nitrosylmyoglobin (MbNO), oxymyoglobin (MbO(2)), cyanomyoglobin (MbCN), aquomet myoglobin (metMb) and unligated myoglobin (deoxyMb) in physiological media. The analysis of the XAN ...

2014

A Vibronic Coupling Hamiltonian to Describe the Ultrafast Excited State Dynamics of a Cu(I)-Phenanthroline Complex

Ursula Röthlisberger, Ivano Tavernelli, Thomas James Penfold, Gloria Capano

We present a model Hamiltonian to study the nonadiabatic dynamics of photoexcited Cu(dmp)(2), (dmp = 2,9-dimethyl-1,10-phenanthroline). The relevant normal modes, identified by the magnitude of the first order coupling constants, correspond closely to ...

2014

Derivation of spin-orbit couplings in collinear linear-response TDDFT: A rigorous formulation

Ivano Tavernelli, Basile Curchod, Thomas James Penfold

Using an approach based upon a set of auxiliary many-electron wavefunctions we present a rigorous derivation of spin-orbit coupling (SOC) within the framework of linear-response time-dependent density functional theory (LR-TDDFT). Our method is based on a ...

2014

X-ray Spectroscopic Study of Solvent Effects on the Ferrous and Ferric Hexacyanide Anions

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold

We present an Fe K alpha resonant inelastic X-ray scattering (RIXS) and X-ray emission (XES) study of ferrous and ferric hexacyanide dissolved in water and ethylene glycol. We observe that transitions below the absorption edge show that the solvent has a d ...

2014

Hydrophobicity with atomic resolution: Steady-state and ultrafast X-ray absorption and molecular dynamics studies

Majed Chergui, Ivano Tavernelli, Thomas James Penfold

Static and time-resolved X-ray absorption spectroscopy (XAS) is used to probe the solvent shell structure around iodide and iodine. In particular, we characterize the changes ob served upon electron abstraction of aqueous iodide, which reflects the transit ...

De Gruyter2013

The role of Hartree-Fock exchange in the simulation of X-ray absorption spectra: A study of photoexcited [Fe(bpy)(3)](2+)

Majed Chergui, Ursula Röthlisberger, Ivano Tavernelli, Marco Eli Reinhard, Mercedes Hannelore Rittmann-Frank, Thomas James Penfold, Gloria Capano

We present a theoretical analysis for the K- and L-2/3-edge static and picosecond X-ray absorption spectra of Fe(bpy)(3). Simulations of the pre-edge region at the Fe K-edge using time-dependent density functional theory demonstrate the importance of ...

Elsevier2013