Laser-assisted XUV double ionization of helium: Energy-sharing dependence of joint angular distributions

Liu, Aihua; Thumm, Uwe

doi:10.1103/physreva.91.043416

Cited by 16 publications

(15 citation statements)

References 36 publications

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“…The units are arbitrary. and we can see the appearance of the two photoelectrons with the same energy in back-to-back emission [19,20]. For emission of one laser photon, the total excess energy become less and the probability with any energy sharing ratio is almost the same.…”

Section: Resultsmentioning

confidence: 91%

Laser-assisted two-color two-photon double ionization of helium atoms

Zhu

Zhang

et al. 2021

Preprint

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Correlated momentum and kinetic energy distributions of two photoelectrons in laser-assisted two-color two-photon double ionization of helium are investigated by numerically solving a one-plus-one dimensional time-dependent Schr\"{o}dinger equation (TDSE). We find that the weak assisting laser field can act as an energy transferring field, resulting in burst of double ionization. More importantly, the participation of the laser photon into the double ionization reshapes the correlation patterns in the momentum and kinetic energy distributions. The laser photon can be absorbed by any one of the two electrons, providing two channels that induces destructive interference in the correlated momentum and kinetic energy distributions, which is never found in previous work.

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Section: Resultsmentioning

confidence: 91%

Laser-assisted two-color two-photon double ionization of helium atoms

Zhu

Zhang

et al. 2021

Preprint

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“…The additionally emerging rings in Figs. 2(a and we can see the appearance of the two photoelectrons with the same energy in back-to-back emission [19,20]. For emission of one laser photon, the total excess energy become less and the probability with any energy sharing ratio is almost the same.…”

Section: Resultsmentioning

confidence: 92%

Laser-assisted two-color two-photon double ionization of helium atoms

Zhu

Zhang

et al. 2021

Opt Quant Electron

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Correlated momentum and kinetic energy distributions of two photoelectrons in laser-assisted two-color two-photon double ionization of helium are investigated by numerically solving a one-plus-one dimensional timedependent Schrödinger equation (TDSE). We find that the weak assisting laser field can act as an energy transferring field, resulting in burst of double ionization. More importantly, the participation of the laser photon into the double ionization reshapes the correlation patterns in the momentum and kinetic energy distributions. The laser photon can be absorbed by any one of the two electrons, providing two channels that induces destructive interference in the correlated momentum and kinetic energy distributions, which is never found in previous work.

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“…This weak dependence on ε is also seen in the mutual angular distributions for ℏω ctr ¼ 90 eV in Fig. 1(d), which display doubleionization yields as a function of θ 12 and are normalized individually to the total (angle-integrated) yield [16].…”

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confidence: 77%

“…Two-photon double ionization is much more difficult to detect than singlephoton double ionization due to its extremely small total cross section (≈10 −52 cm 4 s) [17][18][19]. It was first measured in 2005 [18], followed by many theoretical studies [16,17,[19][20][21][22][23][24][25].…”

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confidence: 99%

“…The adjustable parameter, θ 1=2 , is related to the significance of correlation in the double-ionization process [11]. The antisymmetrical contribution and back-to-back electron emission vanish at equal energy sharing but become progressively more prominent for increasingly nonequal energy sharing, as the antisymmetrical contribution j cos θ 1 − cos θ 2 j 2 gradually appears in joint photoelectron angular distributions [10,11,16]. …”

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confidence: 99%

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Criterion for Distinguishing Sequential from Nonsequential Contributions to the Double Ionization of Helium in Ultrashort Extreme-Ultraviolet Pulses

Liu

Thumm

2015

Phys. Rev. Lett.

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We quantify sequential and nonsequential contributions in two-photon double ionization of helium atoms by intense ultrashort extreme-ultraviolet pulses with central photon energies ℏω ctr near the sequential double-ionization threshold. If the spectrum of such pulses overlaps both the sequential (ℏω > 54.4 eV) and nonsequential (ℏω < 54.4 eV) double-ionization regimes, the sequential and nonsequential doubleionization mechanisms are difficult to distinguish. By tracking the double-ionization asymmetry in joint photoelectron angular distributions, we introduce the two-electron forward-backward-emission asymmetry as a measure that allows the distinction of sequential and nonsequential contributions. Specifically, for ℏω ctr ¼ 50 eV pulses with a sine-squared temporal profile, we find that the sequential double-ionization contribution is the largest at a pulse length of 650 as, due to competing temporal and spectral constraints. In addition, we validate a simple heuristic expression for the sequential double-ionization contribution in comparison with ab initio calculations. DOI: 10.1103/PhysRevLett.115.183002 PACS numbers: 32.80.Rm, 33.80.Rv, 42.50.Hz In 1975, the mechanism of nonsequential double ionization was revealed in the photoionization of alkaline earth atoms [1]. It is enabled by strong electronic correlation and thus clearly distinct from the sequential double-ionization mechanism. Nonsequential double ionization was observed for noble gas atoms in 1982 [2] and received rapidly increasing attention from both experimentalists [3-9] and theorists [10][11][12][13].Photoelectron angular distributions of single-photon double ionization were found to owe their structure partly to (dipole) selection rules [11,14,15] and to consist of symmetrical and antisymmetrical contributions (with regard to electron exchange), that each can be written as the product of an angular and a correlation factor [11]. For coplanar emission geometry, where the emitted-electron momenta and polarization axis of the linearly polarized extremeultraviolet (XUV) pulse lie in a plane, and for equal energy sharing (equal asymptotic kinetic energies E 1 and E 2 of the photoelectrons), the angular factor becomes j cos θ 1 þ cos θ 2 j 2 , where θ 1 and θ 2 are photoelectron emission angles relative to the polarization direction of the ionizing light, while the electron correlation factor follows as expf−4 ln 2½ðθ 12 − πÞ=θ 1=2 2 g, with the mutual emission angle θ 12 ¼ jθ 1 − θ 2 j. The adjustable parameter, θ 1=2 , is related to the significance of correlation in the double-ionization process [11]. The antisymmetrical contribution and back-to-back electron emission vanish at equal energy sharing but become progressively more prominent for increasingly nonequal energy sharing, as the antisymmetrical contribution j cos θ 1 − cos θ 2 j 2 gradually appears in joint photoelectron angular distributions [10,11,16].

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Laser-assisted XUV double ionization of helium: Energy-sharing dependence of joint angular distributions

Cited by 16 publications

References 36 publications

Laser-assisted two-color two-photon double ionization of helium atoms

Laser-assisted two-color two-photon double ionization of helium atoms

Laser-assisted two-color two-photon double ionization of helium atoms

Criterion for Distinguishing Sequential from Nonsequential Contributions to the Double Ionization of Helium in Ultrashort Extreme-Ultraviolet Pulses

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