Plateau in above-threshold-ionization spectra and chaotic behavior in rescattering processes

HuP, Bambi; Liu, Jie; Chen, Shigang

doi:10.1016/s0375-9601(97)00811-6

Cited by 122 publications

(94 citation statements)

References 15 publications

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“…The initial value of the coordinate is defined either by the Field Direction Model (FDM)10 or, in a more refined approach based on use of the parabolic coordinate system16, as a point at which electron emerges from under the barrier. This separation of the tunnelling ionization process in the quantum-mechanical part, describing the ionization event proper, and the classical part, describing subsequent motion, has been extremely fruitful, as it allows us to consider processes occurring in the strong laser field for systems that are too complex to allow an ab initio quantum mechanical (QM) treatment.…”

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Exit point in the strong field ionization process

Ivanov

Nam

Kim

2017

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We analyze the process of strong field ionization using the Bohmian approach. This allows retention of the concept of electron trajectories. We consider the tunnelling regime of ionization. We show that, in this regime, the coordinate distribution for the ionized electron has peaks near the points in space that can be interpreted as exit points. The interval of time during which ionization occurs is marked by a quick broadening of the coordinate distribution. The concept of the exit point in the tunneling regime, which has long been assumed for the description of strong field ionization, is justified by our analysis.

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confidence: 99%

Exit point in the strong field ionization process

Ivanov

Nam

Kim

2017

Sci Rep

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“…the ratio between the tunneling time of the outer electron and the inverse optical frequency (Keldysh parameter) is less than 1. In this regime, the quasistatic model [5] provides a perfect description for the Hydrogen-like atoms in the intense fields and successfully explain the most nonlinear phenomena observed experimentally [5,10,11]. Inspired by this success, in this paper we extend to develop a 3D quasistatic model (a two step process) to investigate the mechanism of the double ionization of Helium by tracing the classical trajectories of the two correlated electrons.…”

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Classical collisional trajectories as the source of strong-field double ionization of helium in the knee regime

et al. 2001

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In this paper, a quasistatic model is extended to describe the double ionization of Helium in intense linearly polarized field, yielding achieve an insight to the two-electron correlation effect in the ionization dynamics. Our numerical calculations reproduce the excessive double ionization and the photoelectron spectra observed experimentally both quantitatively and qualitatively. Moreover, it is shown that the classical collisional trajectories are the main source of the double ionization in the knee regime and responsible for the unusual angular distribution of the photoelectrons.PACS numbers: 32.80. Rm, 42.50.Hz, Recently the excessive double ionization observed in Helium experiments by Fittinghoff et al. [1], Walker et al.[2], and Sheehy et al. [3] draws much attention to the multiple-electron dynamics in the laser-atom interaction. In these experiments the single ionization yields of He in a linearly polarized field is accurately predicted by the single active electron (SAE) approximation [2], well described by the Ammosov-Delone-Krainov (ADK) tunneling theory [4]. However, the case of double ionization is more complicated. In the regime of very high intensities (I > 10 16 W/cm 2 ) where strong double ionization occurs, the double ionization keeps in good agreement with the sequential SAE models as that in the lower intensities regime(I < 10 14 W/cm 2 ). The double ionization yield deviates seriously from the sequential SAE model and shows a great enhancement in a "knee" regime [(0.8-3.0) × 10 15 W/cm 2 ], where the He 2+ /He + yields ratio is close to a constant: 0.002. This surprising large yields of the double ionization obviously indicates that the sequential ionization is no longer the dominating process in this regime and the electron-electron correlation has to be taken into account.Both the "shake-off" model and the "recollision" model are suggested to describe the electron's correlation [1,3,5,6]. However, none of the two nonsequential ionization (NSI) mechanisms can completely explain the experimental observations. For the "shake-off" model, it can not give the reason for the decrease in the double ionization yields as the polarization of the laser field departs from linear [7][8][9]. In the "recollision" model, the returning electrons are known to have a maximum classical kinetic energy of ∼ 3.2U p (U p = e 2 F 2 /4m e ω 2 ), so one can determine a minimum intensity required for the rescattering electron to have enough energy to excite the inner electron. But the double ionization yields observed in experiments have no such an intensity threshold. In fact, the double ionization process is rather complicated and subtle, both of the two NSI processes and the sequential ionization contribute to the double ionization yields and may dominate in the different regimes.The experiments on the double ionization of Helium are mainly confined in the tunneling regime, i.e. the ratio between the tunneling time of the outer electron and the inverse optical frequency (Keldysh parameter) is less than 1. ...

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“…Our calculation procedure is based on a well-verified numerical method which has been employed successfully to provide physical insight into intense field atomic ionization processes such as ATI and NSDI, see e.g 1119203233…”

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confidence: 99%

Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics

Quan

Hao

Chen

et al. 2016

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In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends.

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Plateau in above-threshold-ionization spectra and chaotic behavior in rescattering processes

Cited by 122 publications

References 15 publications

Exit point in the strong field ionization process

Exit point in the strong field ionization process

Classical collisional trajectories as the source of strong-field double ionization of helium in the knee regime

Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics

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