Probing the Electron Delocalization in Liquid Water and Ice at Attosecond Time Scales

Nordlund, Dennis; Ogasawara, Hirohito; Bluhm, Hendrik; Takahashi, Osamu; Odelius, Michael; Nagasono, Mitsuru; Pettersson, Lars G. M.; Nilsson, Anders

doi:10.1103/physrevlett.99.217406

Cited by 126 publications

(131 citation statements)

References 44 publications

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“…Two recent, independent measurements of the spectator Auger-electron spectrum of liquid water show experimentally that the electron becomes increasingly delocalized as the excitation energy increases. 33,62 Even for the lowest excited state of condensed water, Hahn et al 34 showed that the excited electron is somewhat delocalized onto neighboring molecules, although the excited state is still located primarily on a single water molecule.…”

Section: Fate Of Gas-phase Excited States In Liquid Water and Tentmentioning

confidence: 99%

“…31 An alternate view is one in which the excited molecular orbitals are partially delocalized over one or more neighboring solvent molecules. [32][33][34][35][36] Unfortunately, a clear and consistent theoretical description of the electronically excited states of liquid water is not yet available because accurate electronic structure calculations are extremely difficult for such strongly interacting molecules. [34][35][36][37][38][39][40][41] 2PA spectroscopy provides a new window on the electronic transitions of liquid water because the symmetry selection rules are different than for linear spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Elles¹,

Rivera²,

Zhang³

et al. 2009

The Journal of Chemical Physics

106

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Two-photon absorption ͑2PA͒ spectroscopy in the range from 7 to 10 eV provides new insight on the electronic structure of liquid water. Continuous 2PA spectra are obtained via the pump-probe technique, using broadband probe pulses to record the absorption at many wavelengths simultaneously. A preresonance enhancement of the absolute 2PA cross section is observed when the pump-photon energy increases from 4.6 to 6.2 eV. The absorption cross section also depends on the relative polarization of the pump and probe photons. The variation of the polarization ratio across the spectrum reveals a detailed picture of the 2PA and indicates that at least four different transitions play a role below 10 eV. Theoretical polarization ratios for the isolated molecule illustrate the value of the experimental polarization measurement in deciphering the 2PA spectrum and provide the framework for a simple simulation of the liquid spectrum. A more comprehensive model goes beyond the isolated molecule picture and connects the 2PA spectrum with previous one-photon absorption, photoelectron, and x-ray absorption spectroscopy measurements of liquid water. Previously unresolved, overlapping transitions are assigned for the first time. Finally, the electronic character of the vertical excited states is related to the energy-dependent ionization mechanism of liquid water.

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Section: Fate Of Gas-phase Excited States In Liquid Water and Tentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Elles¹,

Rivera²,

Zhang³

et al. 2009

The Journal of Chemical Physics

106

View full text Add to dashboard Cite

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“…In the excitation spectra, peak 1 appears at somewhat larger KEs due to spectator energy shifts, an effect which previously has been discussed for water in great detail. [41][42] For core-level ionization and excitation the spectral changes between normal and deuterated water are fairly similar; compare the respective differential spectra. Proton dynamics thus seems to be of importance for decays from all intermediate states reached throughout the O1s near-edge absorption fine structure of liquid water (here the delocalized two-hole final state contains an additional excited electron; 1e1h•1h).…”

Section: Core-level Excitation Induced Autoionization Spectra: H 2 O(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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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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“…Here, an electron from the occupied valence levels fills the core hole. The excess energy is transferred to a second electron (Auger electron) from the valence levels, which leaves the molecule with a kinetic energy of about 500 eV [25]. The Auger electron then scatters elastically as well as inelastically at surrounding water molecules (Auger cascade).…”

mentioning

confidence: 99%

Reabsorption of Soft X-Ray Emission at High X-Ray Free-Electron Laser Fluences

et al. 2014

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We report on oxygen K-edge soft x-ray emission spectroscopy from a liquid water jet at the Linac Coherent Light Source. We observe significant changes in the spectral content when tuning over a wide range of incident x-ray fluences. In addition the total emission yield decreases at high fluences. These modifications result from reabsorption of x-ray emission by valence-excited molecules generated by the Auger cascade. Our observations have major implications for future x-ray emission studies at intense x-ray sources. We highlight the importance of the x-ray pulse length with respect to the core-hole lifetime.

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Probing the Electron Delocalization in Liquid Water and Ice at Attosecond Time Scales

Cited by 126 publications

References 44 publications

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

Electronic structure of liquid water from polarization-dependent two-photon absorption spectroscopy

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

Reabsorption of Soft X-Ray Emission at High X-Ray Free-Electron Laser Fluences

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