Simulation of above-threshold ionization experiments using the strong-field approximation

Hasović, E.; Busuladžić, M.; Gazibegović-Busuladžić, A.; Milošević, D. B.; Becker, W.

doi:10.1134/s1054660x07040135

Cited by 65 publications

(48 citation statements)

References 41 publications

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“…These experiments have stimulated a number of theoretical efforts aimed at identifying the origin of this effect. Especially intriguing was the discovery that similar enhancements are observed in the ATD process, in which atomic negative ions, instead of neutral atoms, are detached by a laser field [2][3][4][5][6][7][8][9][10][11][12][13]. Based on model calculations employing zero-and finite-range potentials, it was realized that the aforementioned enhancements stem from the behaviors of detachment yields at multiphoton thresholds, which are consistent with predictions of the Wigner threshold law [22].…”

Section: Introductionsupporting

confidence: 61%

“…While threshold effects in ATD are very well understood and confirmed by numerous calculations [2][3][4][5][6][7][8][9][10][11][12][13], similar recent studies devoted to abovethreshold ionization (ATI) or to high-harmonic generation (HHG) (a competing process) reach different conclusions (see, e.g., Refs. [14][15][16]).…”

Section: Introductionmentioning

confidence: 99%

“…Although the threshold behavior of ATD spectra is very well understood owing to a large number of investigations of ATD plateau enhancements [2][3][4][5][6][7][8][9][10][11][12][13], a consistent interpretation of the threshold behavior of ATI and HHG processes for neutral atoms is far less firmly established. In the latter case, one must account for the role of the attractive Coulomb potential, including especially the Rydberg series converging to each multiphoton ionization threshold.…”

Section: Introductionmentioning

confidence: 99%

“…Theoretical analyses of the role of threshold laws in abovethreshold detachment (ATD) by strong laser fields have been carried out in many works [2][3][4][5][6][7][8][9][10][11][12][13]. While threshold effects in ATD are very well understood and confirmed by numerous calculations [2][3][4][5][6][7][8][9][10][11][12][13], similar recent studies devoted to abovethreshold ionization (ATI) or to high-harmonic generation (HHG) (a competing process) reach different conclusions (see, e.g., Refs.…”

Section: Introductionmentioning

confidence: 99%

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Threshold effects in strong-field ionization: Energy shifts and Rydberg structures

2012

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The behavior of strong-field ionization rates of neutral atoms in the vicinity of multiphoton ionization thresholds is analyzed using formal collision theory. Our approach, which accounts nonperturbatively for effects of an intense laser field, shows that the ionization rates have a nearly constant behavior below and above each multiphoton threshold and that between such thresholds there are an apparently finite number of rapid oscillations due to resonances with laser-field-modified Rydberg states. This pattern is typical for any atomic target, as we illustrate specifically for hydrogen and neon atoms. The flat behavior of the ionization yield near multiphoton thresholds gives the appearance of an energy shift of the ionization thresholds, which have been postulated in a number of recent studies concerning diverse aspects of above-threshold ionization and high-harmonic generation of atoms. The flat behaviors of the rates near threshold exhibit only a rather weak dependence on the laser-field intensity. Other aspects of the near-threshold behavior of ionization rates and their dependence on the laser-field parameters are also discussed.

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Section: Introductionsupporting

confidence: 61%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Threshold effects in strong-field ionization: Energy shifts and Rydberg structures

2012

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“…These finger-like structures follow lines of constant ponderomotive energy, UP. These structures are a result of channel-closing effects [32,[73][74][75][76], where excited states undergo such a large ac Stark shift that they are no longer accessible via REMPI. The presence of channel-closing effects is indicative of REMPI, and these channel closings are observed more prominently in linear fields than circular fields [77], since circular fields can only access excited states with high angular momentum.…”

Section: Iiib Tdse Simulationsmentioning

confidence: 99%

Observation of ionization enhancement in two-color circularly polarized laser fields

et al. 2017

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When atoms are irradiated by two-color circularly polarized laser fields the resulting strong field processes are dramatically different than when the same atoms are irradiated by a single-color ultrafast laser. For example, electrons can be driven in complex 2D trajectories before rescattering or circularly polarized high harmonics can be generated, which was once thought impossible. Here, we show that two-color circularly polarized lasers also enable control over the ionization process itself and make a surprising finding: the ionization rate can be enhanced by up to 700% simply by switching the relative helicity of the two-color circularly polarized laser field. This enhancement is experimentally observed in helium, argon and krypton over a wide range of intensity ratios of the twocolor field. We use a combination of advanced quantum and fully classical calculations to explain this ionization enhancement as resulting in part due to the increased density of excited states available for resonance-enhanced ionization in counter-rotating fields compared with co-rotating fields. In the future, this effect could be used to probe the excited state manifold of complex molecules.

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Nondipole Effects in Atomic Ionization Induced by an Intense Counter‐Rotating Bicircular Laser Field

et al. 2023

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Nondipole effects occurring in the process of atomic ionization by an intense, mid-infrared, counter-rotating bicircular laser field are investigated using the strong-field approximation with leading-order nondipole corrections. The time integrals appearing in the expression for the differential ionization rate are computed in two ways: numerically, and by applying the saddle-point approximation. The nondipole corrections introduce an asymmetry in the photoelectron momentum distribution along the field propagation direction. The asymmetry is quantified by the partial average value of the propagation-direction momentum component of the photoelectrons and by the normalized difference of the differential ionization rates computed including and excluding the nondipole corrections. Using the saddle-point approximation, it is investigated how the nondipole corrections change the solutions for direct photoelectrons and how this affects the momentum spectra. The impact of nondipole corrections increases with increasing photoelectron energy. Analysis of the complete photoelectron spectra including both direct and rescattered photoelectrons shows that, in the low-energy region, a shift against the propagation direction occurs. The partial average of the propagation-direction momentum component in the rescattering region exhibits a plateau structure and also a local minimum structure that was recently observed in an experiment with a linearly polarized laser field (Lin et al., Phys Rev. Lett. 128, 023201 (2022)).

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Simulation of above-threshold ionization experiments using the strong-field approximation

Cited by 65 publications

References 41 publications

Threshold effects in strong-field ionization: Energy shifts and Rydberg structures

Threshold effects in strong-field ionization: Energy shifts and Rydberg structures

Observation of ionization enhancement in two-color circularly polarized laser fields

Nondipole Effects in Atomic Ionization Induced by an Intense Counter‐Rotating Bicircular Laser Field

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