Angular distributions in two-colour two-photon ionization of He

Rey, H. F.; Hart, H. W. van der

doi:10.1088/0953-4075/47/22/225601

Cited by 3 publications

(3 citation statements)

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“…We have verified that this disparity does not arise from a deficiency in our description of the He target. Indeed, calculations employing more elaborate He + basis sets (e.g., incorporating the 3s, 3p and 3d pseudo-orbitals [70,78,79]) yield no significant differences in the predicted momentum distributions. Moreover, for a field analogous to that of Figure 1(a), but linearly polarized in the z-direction, calculations exploiting the established RMT codes [60] suggest an almost identical spectrum in the k x k z -plane (with the same difference of peak heights as in Figures 1(a) and (c)).…”

Section: A Calculation Parametersmentioning

confidence: 99%

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R -matrix-with-time-dependence theory for ultrafast atomic processes in arbitrary light fields

Clarke¹,

Armstrong²,

Brown³

et al. 2018

Phys. Rev. A

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We describe an ab initio and non-perturbative R-matrix with time-dependence theory for ultrafast atomic processes in light fields of arbitrary polarization. The theory is applicable to complex, multielectron atoms and atomic ions subject to ultrashort (particularly few-femtosecond and attosecond) laser pulses with any given ellipticity, and generalizes previous time-dependent R-matrix techniques restricted to linearly polarized fields. We discuss both the fundamental equations, required to propagate the multielectron wavefunction in time, as well as the computational developments necessary for their efficient numerical solution. To verify the accuracy of our approach, we investigate the two-photon ionization of He, irradiated by a pair of time-delayed, circularly polarized, femtosecond laser pulses, and compare photoelectron momentum distributions, in the polarization plane, with those obtained from recent time-dependent close-coupling calculations. The predictive capabilities of our approach are further demonstrated through a study of single-photon detachment from F − in a circularly polarized, femtosecond laser pulse, where the relative contribution of the co-and counter-rotating 2p electrons is quantified. arXiv:1812.00234v1 [physics.atom-ph] 1 Dec 2018

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Section: A Calculation Parametersmentioning

confidence: 99%

“…The He target considered in this work is as discussed in previous R-matrix studies [70,78,79]. Within the inner region, we regard the atomic system as He + to which is added a single electron.…”

Section: A Calculation Parametersmentioning

confidence: 99%

R -matrix-with-time-dependence theory for ultrafast atomic processes in arbitrary light fields

Clarke¹,

Armstrong²,

Brown³

et al. 2018

Phys. Rev. A

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“…The production of extreme-ultraviolet (EUV) pulses using high harmonic generation (HHG) and free-electron lasers (FELs) has led to a resurgence of multiphoton ionization studies in the perturbative intensity regime recently [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Along with experimental techniques, such as velocity map imaging [19,20] or cold target recoil ion momentum spectroscopy [21], the detection of angle-resolved emission of the photoelectron following few-photon ionization of atomic and molecular targets has become possible [11].…”

Section: Introductionmentioning

confidence: 99%

Ionization of helium by an ultrashort extreme-ultraviolet laser pulse

Venzke¹,

Jaroń-Becker²,

Becker³

2020

J. Phys. B: At. Mol. Opt. Phys.

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We theoretically study photoelectron angular distributions and related anisotropy parameters for the competition of one- and two-photon ionization of He in an ultrashort extreme-ultraviolet laser pulse, using numerical results from the time-dependent Schrödinger equation. We explore the transition between the two processes for variation of the pulse duration, peak intensity, and central frequency or photoelectron energy. In the results obtained for fixed pulse parameters the transition and interference between the processes can be observed in the even (β2, β4) and odd (β1, β3) parameters, respectively, while the onset of the impact of three-photon ionization is observed via β5 at high peak intensities. Finally, we show that the transition can be observed via the even anisotropy parameters in pulses without carrier-to-envelope stabilization as well as in free-electron laser pulses with fluctuating pulse shape.

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