Role of elastic scattering in high-order above threshold ionization

Laser-induced electron diffraction (LIED), in which elastic scattering of the returning electron with the parent ion takes place, has been used to extract atomic potential and image molecular structures with sub-Å precision and exposure time of a few femtoseconds. So far, the polarization and exchange effects have not been taken into account in the theoretical calculation of differential cross section (DCS) for the laser-induced rescattering processes. However, the validity of this theoretical treatment has never been verified. In this work, we investigate the polarization and exchange effects on electron impact elastic scattering with rare gas atoms and ions. It is found that, while the exchange effect generally plays a more important role than the polarization effect in the elastic scattering process, the exchange effect is less important on electronion collisions than on electron-atom collisions, especially for scattering in backward direction. In addition, our calculations show that, for electron-atom collisions at incident energies above 50 eV, both the polarization and exchange effects can be safely neglected, while for electron-ion collisions, both the polarization and exchange potentials do not make substantial contributions to the DCS at incident energies above 20 eV and scattering angles larger than 90 • . Our investigation confirms the validity of the current LIED method.

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“…9 in Ref. [31]). The reason is that heavier atoms have more bound electrons, resulting in more complex distributions of the charge density.…”

Section: Resultsmentioning

confidence: 91%

Polarization and exchange effects in elastic scattering of electron with atoms and ions

Chen¹,

Cui

2018

Chinese Phys. B

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“…While the QRS model developed by Lin and coworkers has been widely used to simulate photoelectron energy spectra and two-dimensional momentum distributions for both HATI electrons [8][9][10][11] and HHG spectra [12,13] with great success, there have been fewer investigations of NSDI. To study NSDI, field-free inelastic electron impact excitation cross sections and electron impact ionization cross sections are needed over a broad energy range.…”

Section: Introductionmentioning

confidence: 99%

Ratios of double to single ionization of He and Ne by strong 400-nm laser pulses using the quantitative rescattering theory

Chen

Zatsarinny

et al. 2018

Phys. Rev. A

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We present numerical simulations of the ratio between double and single ionization of He and Ne by intense laser pulses at wavelengths of 390 nm and 400 nm, respectively. The yields of doubly charged ions due to nonsequential double ionization (NSDI) are obtained by employing the quantitative rescattering (QRS) model. In this model, the NSDI ionization probability is expressed as a product of the returning electron wave packet (RWP) and the total scattering cross sections for laser-free electron impact excitation and electron impact ionization of the parent ion. According to the QRS theory, the same RWP is also responsible for the emission of high-energy above-threshold ionization (HATI) photoelectrons. To obtain absolute double-ionization yields, the RWP is generated by solving the time-dependent Schrödinger equation (TDSE) within a one-electron model. The same TDSE results can also be taken to obtain single-ionization yields. By using the TDSE results to calibrate single ionization and the RWP obtained from the strong-field approximation, we further simplify the calculation such that the nonuniform laser intensity distribution in the focused laser beam can be accounted for. In addition, laser-free electron impact excitation and ionization cross sections are calculated using the state-of-the-art many-electron R-matrix theory. The simulation results for double to single ionization ratios are found to compare well with experimental data and support the validity of the nonsequential double ionization mechanism for the covered intensity region.

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“…The validity of Eq. (3) has been extensively verified in the description of laser-induced electron diffraction due to elastic scattering of the electron from the parent ion [16,17,[36][37][38][39]. We note that the factorization formula near the outermost backward rescattering caustic was recently derived from adiabatic theory [40].…”

Section: Excitmentioning

confidence: 80%

Revisiting the recollisional excitation-tunneling process in strong-field nonsequential double ionization of helium

et al. 2019

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We revisit the excitation-tunneling process in nonsequential double ionization (NSDI) of helium in an 800 nm laser field. The correlated two-electron momentum distributions are calculated by using the improved quantitative rescattering (QRS) model, in which the lowering of the threshold energy due to the presence of an electric field at the instant of recollision is taken into account. In the framework of the QRS model, the correlated two-electron momentum distributions for excitationtunneling in NSDI can be factorized as a product of the returning-electron wave packet (RWP) and the field-free differential cross section (DCS) for electron impact excitation of the parent ion multiplied by the tunneling ionization rate of electrons in the excited states. The RWPs, which describe the momentum distribution of the returning electrons, are obtained within the strong-field approximation for high-order above-threshold ionization. The DCSs for electron impact excitation of He + are calculated using the state-of-the-art many-electron R-matrix theory, and the tunneling ionization rates for electrons in the excited states are evaluated by solving the time-dependent Schrödinger equation. The calculated correlated two-electron momentum distribution shows that the fourfold symmetry with regard to the parallel momentum components is broken. This is in contradiction to the prevalent view that the correlation pattern for excitation-tunneling in NSDI is symmetric with respect to the coordinate axes. By including the recollisional (e, 2e) process, the predicted correlated two-electron momentum distributions are found to be in good qualitative agreement with experiment.

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Role of elastic scattering in high-order above threshold ionization

Cited by 7 publications

References 29 publications

Polarization and exchange effects in elastic scattering of electron with atoms and ions

Polarization and exchange effects in elastic scattering of electron with atoms and ions

Ratios of double to single ionization of He and Ne by strong 400-nm laser pulses using the quantitative rescattering theory

Revisiting the recollisional excitation-tunneling process in strong-field nonsequential double ionization of helium

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