Time‐Dependent Density Functional Theory Molecular Dynamics Simulations of Liquid Water Radiolysis

Tavernelli, Ivano; Gaigeot, Marie‐Pierre; Vuilleumier, Rodolphe; Stia, C. R.; Penhoat, Marie‐Anne Hervé du; Politis, M. F.

doi:10.1002/cphc.200800177

Cited by 46 publications

(58 citation statements)

References 63 publications

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“…In contrast to valence ionization, PTM processes tend to lead to more radical centers, and the damage yield is thus higher. Analogous relaxation processes, involving proton transfer and autoionization, seem so far to be exclusive for processes initiated by core 10 ionization. The autoionization processes are closed energetically upon outer valence ionization.…”

Section: Discussionmentioning

confidence: 99%

“…The resulting highly reactive doubly ionized H 2 O 2+ (aq) molecule, with both vacancies (holes) located at the same site (denoted here as 2h state), then undergoes ultrafast Coulomb explosion, forming dominantly O + 2H + . [10][11] In recent years a set of novel non-local autoionization processes has been identified to play an important role in weakly bonded atomic and molecular systems. [12][13][14] One such relaxation process is Intermolecular Coulombic Decay (ICD), initially observed upon innervalence ionization of van der Waals-bonded clusters, 12,[15][16][17] and later also (hydrogen bonded) water clusters.…”

Section: Identifying the Initial Products Of The Interaction Of High-mentioning

confidence: 99%

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On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation

et al. 2013

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Identifying the initial products of the interaction of high-energy radiation with liquidwater is essential for understanding the yield and patterns of damage in aqueous condensed matter, including biological systems. Up until now several fast reactions induced by energetic particles in water could not be observed on their characteristic timescales, and hence some of the reaction intermediates involved, particularly those requiring nuclear motion, have not been considered in describing radiation chemistry.Here, through a combined experimental and theoretical study, we elucidate the ultrafast proton dynamics in the first few femtoseconds after X-ray core-level ionization of liquid water. We show through isotope analysis of the Auger-spectra that proton-transfer dynamics occurs on the same timescale as electron autoionization. Proton transfer leads to formation of a Zundel-type intermediate [HO*··H··OH 2 ] + , which further ionizes, forming a so-far unnoticed type of di-cationic, charge-separated species with high internal energy. We call the process proton-transfer mediated charge separation.The primary processes in water initiated by X-radiation are poorly understood despite their paramount importance in different fields. Understanding the energy and charge redistribution in water upon X-ray photon absorption is vital for a design of more efficient radio-oncology schemes, 1-2 for disentangling the physical basis of genotoxic effects on living tissues, [3][4][5] for minimizing the damage of biological samples during X-ray diffraction 2 experiments, 6 as well as for controlling the performance of nuclear reactors under operating conditions. 7 Current understanding of electron-initiated processes in aqueous systems, following energy deposition, and the subsequent radical chemistry have been recently reviewed. 8 An explicit consideration of radicals and molecular species formed via multiple ionization processes of water, involving for instance atomic oxygen and hydrogen peroxide, can be found in the radiolysis literature, e.g. in refs. 7,9 However, the knowledge of the ultrafast processes and mechanisms in water radiolysis remains to large extent unexplored.In the present work we focus on the processes following O1s core-level ionization of water. The highly excited species formed by the core ionization relaxes primarily via Augerelectron decay. As shown in Figure 1b, Auger decay of a water molecule involves refilling the water core-hole by one of the valence electrons, and the simultaneous emission of another valence electron, the Auger electron, from the same water molecule. The resulting highly reactive doubly ionized H 2 O 2+ (aq) molecule, with both vacancies (holes) located at the same site (denoted here as 2h state), then undergoes ultrafast Coulomb explosion, forming dominantly O + 2H + . [10][11] In recent years a set of novel non-local autoionization processes has been identified to play an important role in weakly bonded atomic and molecular systems. [12][13][14] One such relaxation process is Intermolecu...

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Section: Discussionmentioning

confidence: 99%

Section: Identifying the Initial Products Of The Interaction Of High-mentioning

confidence: 99%

On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation

et al. 2013

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“…However, they are directly damaged in the interatomic processes becoming either singly or doubly ionised. In the case of water solutions the single ionisation will lead to proton transfer reaction producing HO· radical, while doubly ionised water is expected to produce atomic oxygen [29]. The hydroxyl radical is highly reactive and causes oxidative damage to other molecules present in the solution (see e.g.…”

Section: 2mentioning

confidence: 99%

The role of metal ions in X-ray-induced photochemistry

2016

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Metal ions play numerous important roles in biological systems being central to the function of biomolecules. In this letter we show that the absorption of X-rays by these ions leads to a complicated chain of ultrafast relaxation steps resulting in the complete degradation of their nearest environment. We conducted high quality ab initio studies on microsolvated Mg 2+ clusters demonstrating that ionisation of an 1s-electron of Mg leads to a complicated electronic cascade comprising both intra-and intermolecular steps and lasting only a few hundreds femtoseconds.The metal cation reverts to its original charge state at the end of the cascade, while the nearest solvation shell becomes multiply ionised and large concentrations of radical and slow electron species build up in the metal's vicinity. We conclude that such cascades involving metal ions are essential for understanding the radiation chemistry of solutions and radiation damage to metal containing biomolecules.

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“…Only recently, the possibility of quantitatively describing the interaction of projectile atoms with the electronic and ionic system of the host material entirely within first-principles calculations has come within reach. [30][31][32][33][34][35][36][37] These recent advances for realistic materials rely on non-perturbative time-dependent density functional theory (TDDFT), 26 and its implementation in efficient electronic-structure codes. 38,39 At this point, however, there are still many open questions regarding, not only the physics of electronic stopping (e.g.…”

Section: Introductionmentioning

confidence: 99%

Accurate atomistic first-principles calculations of electronic stopping

2015

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We show that atomistic first-principles calculations based on real-time propagation within time-dependent density functional theory are capable of accurately describing electronic stopping of light projectile atoms in metal hosts over a wide range of projectile velocities. In particular, we employ a plane-wave pseudopotential scheme to solve time-dependent Kohn-Sham equations for representative systems of H and He projectiles in crystalline aluminum. This approach to simulate non-adiabatic electron-ion interaction provides an accurate framework that allows for quantitative comparison with experiment without introducing ad-hoc parameters such as effective charges, or assumptions about the dielectric function. Our work clearly shows that this atomistic first-principles description of electronic stopping is able to disentangle contributions due to tightly bound semicore electrons and geometric aspects of the stopping geometry (channeling vs. off-channeling) in a wide range of projectile velocities.

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Time‐Dependent Density Functional Theory Molecular Dynamics Simulations of Liquid Water Radiolysis

Cited by 46 publications

References 63 publications

On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation

On the nature and origin of dicationic, charge-separated species formed in liquid water on X-ray irradiation

The role of metal ions in X-ray-induced photochemistry

Accurate atomistic first-principles calculations of electronic stopping

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