Gauge aspects in multichannel multiphoton ionization

Leone, Cláudio; Bivona, S.; Burlon, R.; Morales, Felipe; Ferrante, G.

doi:10.1103/physreva.40.1828

Cited by 36 publications

(22 citation statements)

References 12 publications

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“…Partly due to the perturbative nature of the SFA, the should-be gauge invariance of physical observables obtained from the LG and the VG differ and the * zhao.zengxiu@gmail.com two gauges turn out to be two distinct approximations, giving qualitatively conflicting results in many studies [13][14][15]. On the other hand, the simplest diatomic molecule H 2 + is a unique one-electron molecular system which allows for almost exact solutions in the field-free case, as well as for accurate treatment in a laser field, with the recently developed nonperturbative methods of solving the three-dimensional (3D) time-dependent Schrödinger equation (TDSE) [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Alignment-dependent ionization of H2+: From multiphoton ionization to tunneling ionization

2012

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We investigate the strong-field ionization for the ground state of H 2 + by numerically solving the threedimensional (3D) time-dependent Schrödinger equation (TDSE), and comparisons have been made among the TDSE, the different versions of molecular strong-field approximation (MO-SFA) and the molecular Ammosov-Delone-Krainov (MO-ADK) approximation. The study shows that, for the TDSE results, the ratio of ionization rates between perpendicular and parallel alignments displays a step-like structure against the Keldysh parameter γ . For small internuclear distances, the transition between the steps are found to be around γ ≈ 1 and is recognized as the competition between the multiphoton ionization (MPI) and tunneling ionization (TI). The ionization is more isotropic in the MPI regime. For large internuclear distances, the transition position shifts to larger γ due to the charge-resonance-enhanced ionization (CREI). Different versions of strong-field ionization theories are compared against the TDSE results.

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Section: Introductionmentioning

confidence: 99%

Alignment-dependent ionization of H2+: From multiphoton ionization to tunneling ionization

2012

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“…The latter may be applied in the length gauge (LG) [4,8] or in the velocity gauge (VG) [7]. Extensive studies of gauge aspects by others [9][10][11][12][13] as well as by us [8,[14][15][16][17] has led us to a present belief of superiority of the LG in the context of S-matrix and strong laser fields. Our present results amplify this conviction.…”

Section: Introductionmentioning

confidence: 99%

Multipeak envelope of the above-threshold-ionization energy spectrum in a strong circularly polarized laser field

Bauer

2012

Phys. Rev. A

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We develop a well-known strong-field approximation in the length gauge for a two-dimensional model atom in a strong circularly polarized laser field. For excited initial states (with the principal quantum number n = 2) outgoing photoelectrons usually show energy spectra with an envelope having two or three peaks: one always below and one always above the ponderomotive energy U P . In contrast, for the ground state (with n = 1) there is always a single peak near U P . Our numerical calculations show that the multipeak effect appears for sufficiently high laser intensities I and is more pronounced for higher laser frequencies ω. We believe that the field parameters ω and I , for which the multipeak envelope in the energy spectrum of above-threshold ionization exists, will enable its experimental observation in the near future.

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“…The selection rule in (13) In order to continue our analytic evaluation of (13), we have to restrict ourselves to the consideration of moderate laser field intensities of about I = (1012 + 1018)Wcm-2 for a NdYAG laser, since in that case b = :/2hoJ << 1 and we can replace BN(-dz;b) by JN(-az) in (14) and thus in (13). The selection rule in (13) In order to continue our analytic evaluation of (13), we have to restrict ourselves to the consideration of moderate laser field intensities of about I = (1012 + 1018)Wcm-2 for a NdYAG laser, since in that case b = :/2hoJ << 1 and we can replace BN(-dz;b) by JN(-az) in (14) and thus in (13).…”

Section: [-1 = [-1~ + V(x)mentioning

confidence: 99%

“…By replacing B N by JN in (13) and by using (17), we can now perform all the summations over N and we can evaluate the integration over z. For the remaining integration over p in (13) we introduce the parameters ~ and we evaluate Uo (p) and…”

Section: [-1 = [-1~ + V(x)mentioning

confidence: 99%

Harmonic generation in keldysh-type models

Ehlotzky

1992

Il Nuovo Cimento D

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We shall investigate two models of harmonic generation in the spirit of the Keldysh theory and we shall apply these models to hydrogen, for which more exact data for the rates of this process are available. Although our models correctly describe the angular distribution, the intensity dependence (in the perturbation regime) and the selection rule for odd harmonics, they badly fail in their predictions of the correct order of magnitude of the rates, in particular, of the formation of a plateau. These latter findings disagree with the results of a similar model calculation by Becker et al. for a ~-function potential.PACS 72.20 -Conductivity phenomena in semiconductors and insulators. PACS 42.65 -Nonlinear apics.

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Gauge aspects in multichannel multiphoton ionization

Cited by 36 publications

References 12 publications

Alignment-dependent ionization of H2+: From multiphoton ionization to tunneling ionization

Alignment-dependent ionization of H2+: From multiphoton ionization to tunneling ionization

Multipeak envelope of the above-threshold-ionization energy spectrum in a strong circularly polarized laser field

Harmonic generation in keldysh-type models

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