Two-photon double ionization of helium: investigating the importance of correlation in the final state

Simonsen, Aleksander Skjerlie; Askeland, Sigurd; Førre, Morten

doi:10.2478/s11534-013-0180-x

Cited by 4 publications

(5 citation statements)

References 41 publications

(47 reference statements)

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“…II, the process of extracting the double-continuum component is associated with an error which is controlled by the postpropagation technique. As found in similar studies [16,24], the error is relatively small (of the order of a few percent) and diminishes rapidly only with a few cycles of postpropagation.…”

Section: Resultssupporting

confidence: 69%

“…The computational details of our scheme are described in [19], and it has been applied successfully to the study of various laser-induced processes in two-electron systems [19,20,24,36,[45][46][47]. A short summary of the numerical details will be reiterated here for the convenience of the reader.…”

Section: Theory and Methodologymentioning

confidence: 99%

“…Indeed, the electron-electron correlation is not built into such product states, but in the asymptotic regime where the electrons are spatially well separated, the electron-electron interaction plays a minor role. The accuracy of this method has been investigated (see, for instance, [16,24]), and it is found that the associated error is small and can be controlled by a technique known as postpropagation. The idea is simply to expose the final wave function to field-free time propagation in order to let the ionized electrons drift apart and hence reduce the importance of the electron-electron repulsion in 043427-2 the continuum components.…”

Section: Theory and Methodologymentioning

confidence: 99%

“…This interval is of special interest as here the direct TPDI process can be studied separately from the sequential one. Being the simplest two-electron system, * aleksander.simonsen@ift.uib.no † morten.forre@ift.uib.no helium was the first target of considerable theoretical [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and experimental [26][27][28][29][30][31] interest. Other two-electron systems have also been investigated, including TPDI of fixed-in-space H 2 [32][33][34][35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

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Two-photon double ionization of metastable1,3S1s2shelium

2014

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We investigate the process of two-photon double ionization (TPDI) of the metastable helium 1,3 S 1s2s states. The process has been simulated within a fully ab initio numerical framework, solving the time-dependent Schrödinger equation in full dimensionality for the two interacting electrons, in a B-spline-based methodology. The presence of doubly excited (autoionizing) states in the direct TPDI regime causes resonance-enhanced multiphoton ionization, and we demonstrate this effect by accessing the 1,3 P 2s2p doubly excited states. Fully converged theoretical calculations are presented, and a well-defined cross section is extracted for the direct TPDI process and compared in the context of its analogous process in the helium ground state. In addition, the resonance-enhanced two-photon double-ionization mechanism is explored, and we discuss how this process differs from both direct and sequential ionization processes.

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Section: Resultssupporting

confidence: 69%

Section: Theory and Methodologymentioning

confidence: 99%

Section: Theory and Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Two-photon double ionization of metastable1,3S1s2shelium

2014

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“…This causes the mean distance between the ionized electrons to increase rapidly, thus reducing the importance of the electron-electron interaction. It is usually found that the error associated with such an approach becomes small after only a few cycles of postpropagation [9,17].…”

Section: B the Full Solutionmentioning

confidence: 99%

Distinction between sequential and direct ionization in two-photon double ionization of helium

et al. 2014

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This paper aims to shed some light on the role of the direct, or nonsequential, ionization channel in the regime in which the sequential channel is open in two-photon double ionization (TPDI) of helium. In this regime the sequential channel dominates any direct contribution unless the laser pulse is of very short duration, in which case their distinction is hard to draw. Based on both a simple model and full solutions of the time-dependent Schrödinger equation, we aim to provide evidence of direct double ionization by identifying a term proportional to the pulse duration in the double ionization yield. Indeed, such a term is identified in the energy-differential yield. When it comes to the total double ionization probability, however, it turns out that the net first-order contribution is negative. The nature of the negative first-order contribution is discussed, and we argue that it is of correlated origin.

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Correlated Coulomb-Volkov approach and its application to the angular distributions of two-photon double ionization of helium

Denabe,

Mengoue,

Kwato Njock

2024

Phys. Rev. A

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We investigate the double-ionization process of helium in brief and intense laser fields of 10, 16, and 40 optical cycles, linearly polarized with an intensity of 5×1012Wcm−2. We calculate the total two-photon double-ionization cross section for photon energies ranging from 39.5 to 54 eV and the triple-differential cross sections at a photon energy of 42 eV, using the correlated Coulomb-Volkov approach, which takes into account the interaction of the laser field with each electron (Volkov phase) and interactions of Coulombian nature between electrons and between electrons and the nucleus. The proposed wave function has the advantage of being much less time consuming due to the fact that it does not require a numerical propagation of the wave packet. The results of our calculations obtained for the nonsequential double photoionization are compared with previously reported data and good agreement is found with approaches using projections onto uncorrelated continuum states. This indicates that the disagreements that remain between some theoretical models for the process studied cannot simply be attributed to the electronic correlation in the continuum states. Published by the American Physical Society 2024

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Two-photon double ionization of helium: investigating the importance of correlation in the final state

Cited by 4 publications

References 41 publications

Two-photon double ionization of metastable1,3S1s2shelium

Two-photon double ionization of metastable1,3S1s2shelium

Distinction between sequential and direct ionization in two-photon double ionization of helium

Correlated Coulomb-Volkov approach and its application to the angular distributions of two-photon double ionization of helium

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