Cross Sections for Low-Energy (1–100 eV) Electron Elastic and Inelastic Scattering in Amorphous Ice

Michaud, M.; Wen, A.T.; Sanche, Léon

doi:10.1667/0033-7587(2003)159[0003:csflee]2.0.co;2

Cited by 212 publications

(339 citation statements)

References 81 publications

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“…47,48,55,56 It has to be pointed out, that photoelectron spectroscopy is in general a surface sensitive technique due to the limited escape depth of photoelectrons. In water, the escape depth of photoelectrons with kinetic energies of about 20-30 eV -the kinetic energies relevant to our experiment -is about a few nanometers [57][58][59][60] and thus about several layers of water molecules from the surface only. 61 Therefore, the experiment senses the interface and the condensed phase at t = 0 and the evolution of the hot superheated phase at t 4 0.…”

Section: Introductionmentioning

confidence: 82%

Hydrogen bond dynamics of superheated water and methanol by ultrafast IR-pump and EUV-photoelectron probe spectroscopy

Vöhringer‐Martinez

Link

Lugovoy

et al. 2014

Phys. Chem. Chem. Phys.

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Supercritical water and methanol have recently drawn much attention in the field of green chemistry. It is crucial to an understanding of supercritical solvents to know their dynamics and to what extent hydrogen (H) bonds persist in these fluids. Here, we show that with femtosecond infrared (IR) laser pulses water and methanol can be heated to temperatures near and above their critical temperature T c and their molecular dynamics can be studied via ultrafast photoelectron spectroscopy at liquid jet interfaces with high harmonics radiation. As opposed to previous studies, the main focus here is the comparison between the hydrogen bonded systems of methanol and water and their interpretation by theory. Superheated water initially forms a dense hot phase with spectral features resembling those of monomers in gas phase water. On longer timescales, this phase was found to build hot aggregates, whose size increases as a function of time. In contrast, methanol heated to temperatures near T c initially forms a broad distribution of aggregate sizes and some gas. These experimental features are also found and analyzed in extended molecular dynamics simulations. Additionally, the simulations enabled us to relate the origin of the different behavior of these two hydrogen-bonded liquids to the nature of the intermolecular potentials. The combined experimental and theoretical approach delivers new insights into both superheated phases and may contribute to understand their different chemical reactivities.

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Section: Introductionmentioning

confidence: 82%

Hydrogen bond dynamics of superheated water and methanol by ultrafast IR-pump and EUV-photoelectron probe spectroscopy

Vöhringer‐Martinez

Link

Lugovoy

et al. 2014

Phys. Chem. Chem. Phys.

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“…For this purpose, nine more phonon and vibrational excitation states and the formation of two transient anion states were considered in addition to each of the five ionisation and electronic excitation levels. The total cross sections for these additional physical processes were taken directly from Michaud et al (2003). The energy loss for each level was determined by random sampling from a Lorentzian probability distribution function (PDF).…”

Section: Interaction Cross Section Data In Ptra and Geant4-dnamentioning

confidence: 99%

“…The energy loss for each level was determined by random sampling from a Lorentzian probability distribution function (PDF). The maximum of the PDF was at the mean excitation energy of each excitation state, provided by Michaud et al (2003), and a full width half maximum as suggested by Dingfelder et al (2008). Following the example of Dingfelder et al (2008), the scattering angle after phonon and vibrational excitation were assumed to be the same as for elastic scattering, while dissociative attachment anion states were assumed to not lead to a change in direction.…”

Section: Interaction Cross Section Data In Ptra and Geant4-dnamentioning

confidence: 99%

“…Due to the absence or unreliability of measured interaction cross sections in the condensed phase, track structure simulations generally utilise physical interaction cross sections for water that rely on measurements in water vapour, supplemented by extrapolations and theoretical models for condensed-phase effects (Dingfelder et al, 1998;Emfietzoglou and Nikjoo, 2005;Kutcher and Green, 1976;Rudd et al, 1992). The interaction between neighbouring molecules and the modification of the inter-and intra-molecular structure lead to significant changes of interaction cross sections, to energy shifts and a reduced amplitude of vibrational excitations as well as to additional collective modes of energy loss in the condensed phase compared to the gas phase (Michaud et al, 2003;Sanche et al, 1995). The existing cross section data for liquid water utilised in track structure simulations therefore contain an unknown bias.…”

Section: Introductionmentioning

confidence: 99%

“…A difference between the two states of water might, though, arise from thermal fluctuations, which are increased for the liquid state of water due to the higher temperature and the resulting higher amplitude of molecular vibrations (Michaud et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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Electron emission from amorphous solid water after proton impact: Benchmarking PTra and Geant4 track structure Monte Carlo simulations

Bug

Rabus

Rosenfeld

2012

Radiation Physics and Chemistry

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Track structure Monte Carlo simulations of ionising radiation in water are often used to estimate radiation damage to DNA. For this purpose, an accurate simulation of the transport of densely ionising low-energy secondary electrons is particularly important, but is impaired by a high uncertainty of the required physical interaction cross section data of liquid water.A possible tool for the verification of the secondary electron transport in a track structure simulation has been suggested by Toburen et al. (2010), who have measured the angle-dependent energy spectra of electrons, emitted from a thin layer of amorphous solid water (ASW) upon a passage of 6. MeV protons.In this work, simulations were performed for the setup of their experiment, using the PTB Track structure code (PTra) and Geant4-DNA. To enable electron transport below the ionisation threshold, additional excitation and dissociative attachment anion states were included in PTra and activated in Geant4. Additionally, a surface potential was considered in both simulations, such that the escape probability for an electron is dependent on its energy and impact angle at the ASW/vacuum interface.For vanishing surface potential, the simulated spectra are in good agreement with the measured spectra for energies above 50. eV. Below, the simulations overestimate the yield of electrons by a factor up to 4 (PTra) or 7 (Geant4-DNA), which is still a better agreement than obtained in previous simulations of this experimental situation. The agreement of the simulations with experimental data was significantly improved by using a steplike increase of the potential energy at the ASW surface. 2012 Elsevier Ltd. AbstractTrack structure Monte Carlo simulations of ionising radiation in water are often used to estimate radiation damage to DNA. For this purpose, an accurate simulation of the transport of densely ionising low-energy secondary electrons is particularly important, but is impaired by a high uncertainty of the required physical interaction cross section data of liquid water.A possible tool for the verification of the secondary electron transport in a track structure simulation has been suggested by Toburen et al. (2010), who have measured the angle-dependent energy spectra of electrons, emitted from a thin layer of amorphous solid water (ASW) upon a passage of 6 MeV protons.In this work, simulations were performed for the setup of their experiment, using the PTB Track structure code (PTra) and Geant4-DNA. To enable electron transport below the ionisation threshold, additional excitation and dissociative attachment anion states were included in PTra and activated in Geant4.Additionally, a surface potential was considered in both simulations, such that the escape probability for an electron is dependent on its energy and impact angle at the ASW/vacuum interface.For vanishing surface potential, the simulated spectra are in good agreement with the measured spectra for energies above 50 eV. Below, the simulations overestimate the yield of electrons by a ...

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Geant4‐DNA example applications for track structure simulations in liquid water: A report from the Geant4‐DNA Project

et al. 2018

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This Special Report presents a description of Geant4-DNA user applications dedicated to the simulation of track structures (TS) in liquid water and associated physical quantities (e.g., range, stopping power, mean free path…). These example applications are included in the Geant4 Monte Carlo toolkit and are available in open access. Each application is described and comparisons to recent international recommendations are shown (e.g., ICRU, MIRD), when available. The influence of physics models available in Geant4-DNA for the simulation of electron interactions in liquid water is discussed. Thanks to these applications, the authors show that the most recent sets of physics models available in Geant4-DNA (the so-called "option4" and "option 6" sets) enable more accurate simulation of stopping powers, dose point kernels, and W-values in liquid water, than the default set of models ("option 2") initially provided in Geant4-DNA. They also serve as reference applications for Geant4-DNA users interested in TS simulations.

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Cross Sections for Low-Energy (1–100 eV) Electron Elastic and Inelastic Scattering in Amorphous Ice

Cited by 212 publications

References 81 publications

Hydrogen bond dynamics of superheated water and methanol by ultrafast IR-pump and EUV-photoelectron probe spectroscopy

Hydrogen bond dynamics of superheated water and methanol by ultrafast IR-pump and EUV-photoelectron probe spectroscopy

Electron emission from amorphous solid water after proton impact: Benchmarking PTra and Geant4 track structure Monte Carlo simulations

Geant4‐DNA example applications for track structure simulations in liquid water: A report from the Geant4‐DNA Project

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