Screening effects and total cross sections of single, double and triple ionization of neon by fast electrons

Defrance, Pierre; Jureta, Jozo; Kereselidze, Tamaz; Lecointre, Julien; Machavariani, Z. S.

doi:10.1088/0953-4075/42/2/025202

Cited by 9 publications

(7 citation statements)

References 39 publications

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“…The values of K [see Eqs. (4) and (20)] are indicated in the figure captions. Figures 1(a), 2(a), and 3(a) give the results of our calculations with electron correlations treated fully in both the initial and the final states for various pairs of electron energy.…”

Section: Resultsmentioning

confidence: 99%

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Two-photon double ionization of atoms in attosecond x-ray radiation fields

et al. 2010

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We consider two-photon double ionization of helium with 100, 200, and 400 eV excess energy for the two ejected electrons, corresponding to photon energies of 89.5, 139.5, and 239.5 eV, respectively. We focus on the case of ultrashort pulses (two oscillations of the field) and develop an approach to calculate the two-photon transition matrix elements within the lowest order of the time-dependent perturbation theory. One of the major difficulties in calculating such amplitudes is the infinite summation over a complete set of intermediate states.In the subfemtosecond regime, however, this summation can be performed accurately by means of the closure approximation. This results in a simple expression for the two-photon amplitude that contains a dipole term and a quadrupole term. The dipole term can be clearly associated to a process in which each electron absorbs a photon whereas the quadrupole term is associated to a process in which one electron absorbs two photons and ejects the second one by collision. We analyze in detail how the relative weight of both processes influences the behavior of the electron energy and angular distributions. In particular we study how the shape of these distributions changes with the amount of electron correlations taken into account in both initial and final states. For 100 eV excess energy, our results for the electron energy distribution are compared with those obtained by solving the time-dependent Schrödinger equation. All these results unveil the crucial role of electron correlations in this transient regime of ionization which is neither sequential nor direct.

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Section: Resultsmentioning

confidence: 99%

“…electron ejection following the emission of a first slow electron after a direct collision of the projectile with the target electron is not clear. A theoretical analysis of the matrix element requires the calculation of n > 2 electron continuum wave functions; this problem is not properly solved (see, for example, [4]). …”

Section: Introductionmentioning

confidence: 99%

Two-photon double ionization of atoms in attosecond x-ray radiation fields

et al. 2010

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“…This conclusion forces us to assume that there are strong correlations among slow electrons in the final state of the reaction, which calls for a dedicated examination. An attempt at such a study was made in [72] within the framework of the effective charge method and looks effective, although still complicated if it were to be carried out in actual calculations.…”

Section: Multiple Ionization Of Noble Gas Atoms By a Fast Electronmentioning

confidence: 99%

Multiple ionization processes involving fast charged particles

et al. 2010

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“…In addition, we assume that the remaining electrons in the doubly charged ion core are unaffected by the ionization process. Under these conditions, the initial state of the system is characterized by the product of an incident plane wave with a molecular target wave function while the final state is described by the product of a scattered plane wave with two independent Coulomb wave functions as well as an approximate expression of the Gamov factor for modeling the electron-electron repulsion [24,25]. Finally, in order to go beyond the domain of validity of the first Born approximation and then to extend the current water molecule double ionization modeling down to the intermediate energy regime, we followed the recommendations of Behati et al who suggested to use an approximate Coulomb wave function of effective charge Z* to represent the scattered electron in the field created by the water nucleus together with the two ejected electrons [26][27][28].…”

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confidence: 99%

“…where gG(k\ , k2) refers to the approximate expression for the repulsive Gamov factor given by Defrance and co-workers [24,25]:…”

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confidence: 99%

H2Odouble ionization induced by electron impact

2015

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Double ionization of water molecules remains, still today, rarely investigated on both the experimental and the theoretical side. In this context, the present work reports on a quantum mechanical approach providing a quantitative description of the electron-induced double ionization process on isolated water molecules for impact energies ranging from the target ionization threshold up to about 10 keV. The cross section calculations are here performed within the first Born approximation framework in which the initial state of the system includes a molecular ground-state wave function expressed as a single-center linear combination of atomic orbitals while the final state of the system is characterized by two independent Coulomb wave functions used for describing the two ejected electrons coupled by a Gamov factor used for modeling the electron-electron repulsion. Besides, in order to go beyond the first Born approximation, the scattered electron is considered as a particle being in the Coulomb field of the nucleus-whose charge is screened by the ejected electrons-and then treated by an approximate Coulomb wave function. In this perturbative-type description, let us add that the passive (not ionized) electrons are considered as frozen in their molecular orbitals during the collision which permits to reduce the electron-target interaction potential to a two-active-electron problem. Comparisons with rare available experimental data are reported as well an energetic analysis in terms of mean secondary energy transfer during the double ionization process in order to demonstrate the relevance of the electron-induced double ionization process.Electron-induced interactions in water are of great impor tance in many fields of research ranging from astrophysics to cellular biology with significant impacts in radiobiology, med ical imaging, and radiotherapy, essentially due to the fact that water is commonly used as a surrogate of the living matter. In this context, it is nowadays well recognized that the "physics" stage that takes place at the first postirradiation femtoseconds plays a key role in the avalanche of events occurring throughout the water radiolysis and then appears as a decisive step in the induction of the radiation cellular damages [1], Under these conditions, accurate cross sections-related to the different electron-induced interactions on water molecules-appear as crucial input data for the numerical codes devoted to the electron track-structure description in biological matter [2]. In this context, the single collisional processes induced by electron impact in water (including the elastic and inelastic channels) have been intensively investigated on both the theo retical [3,4] and the experimental [5,6] sides. Comparatively, the electron-impact double ionization (DI) of water molecules is less documented and therefore generally neglected in the majority of existing numerical track-structure codes arguing a presupposed minor contribution in the total energy deposit pattern. However, whether it is in the wat...

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Screening effects and total cross sections of single, double and triple ionization of neon by fast electrons

Cited by 9 publications

References 39 publications

Two-photon double ionization of atoms in attosecond x-ray radiation fields

Two-photon double ionization of atoms in attosecond x-ray radiation fields

Multiple ionization processes involving fast charged particles

H2Odouble ionization induced by electron impact

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