Trends in the theory of atomic photoionization

Starace, Anthony F.

doi:10.1364/ao.19.004051

Cited by 39 publications

(15 citation statements)

References 80 publications

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“…Techniques such as R-matrix theory [20] and random phase approximation with exchange (RPAE) [21] incorporate interchannel coupling as a perturbation, while the relativistic random phase approximation (RRPA) [22,23], in addition, also includes the relativistic effects. PICSs calculated using the RRPA match very well with the experimental measurements [24]. As we will see in Sec.…”

Section: Introductionsupporting

confidence: 79%

Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation

et al. 2013

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Transition of an electron from a free to a bound state is critical in determining the qualitative shape of the spectrum in high-order-harmonic generation (HHG), and in tomographic imaging of orbitals. We calculate and compare the recombination amplitude, from a continuum state described by a plane wave and an outgoing scattering eigenstate, to the bound state for the noble gases that are commonly used in HHG. These calculations are based on the single active electron model and the Hartree-Fock-Slater method, using both the length form and the acceleration form of the dipole matrix element. We confirm that the recombination amplitude versus emitted photon energy strongly depends upon the wave function used to describe the free electron. Depending on the choice of the wave function and the dipole form, the square of the absolute value of the recombination amplitude can differ by almost two orders of magnitude near the experimentally measured Cooper minima. Moreover, only the outgoing scattering eigenstates with the length form roughly predict the experimentally observed Cooper minimum for Ar (∼50 eV) and Kr (∼85 eV). We provide a detailed derivation of the photorecombination cross sections from photoionization cross sections (PICSs) calculated by the relativistic random phase approximation (RRPA). For Ar, Kr, and Xe, we compare the total PICSs calculated using our recombination amplitudes with that obtained from RRPA. We find that PICS calculated using the outgoing scattering eigenstates with the length form is in better agreement with the RRPA calculations than the acceleration form.

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Section: Introductionsupporting

confidence: 79%

Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation

et al. 2013

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“…[61], the most prominent features in the 3s photoionization partial cross section and total cross section, come from the resonances of the type 3p 4 Table III. Most values agree with the experiment within 1 eV.…”

Section: Appendixmentioning

confidence: 99%

Multiconfigurational Hartree-Fock close-coupling ansatz: Application to the argon photoionization cross section and delays

et al. 2013

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We present a robust, ab initio method for addressing atom-light interactions and apply it to photoionization of argon. We use a close-coupling ansatz constructed on a multiconfigurational Hartree-Fock description of localized states and B-spline expansions of the electron radial wave functions. In this implementation, the general many-electron problem can be tackled thanks to the use of the ATSP2K libraries [C. Froese Fischer et al., Comput. Phys. Commun. 176, 559 (2007)]. In the present contribution, we combine this method with exterior complex scaling, thereby allowing for the computation of the complex partial amplitudes that encode the whole dynamics of the photoionization process. The method is validated on the 3s3p 6 np series of resonances converging to the 3s extraction. Then, it is used for computing the energy dependent differential atomic delay between 3p and 3s photoemission, and agreement is found with the measurements of Guénot et al. [ Phys. Rev. A 85, 053424 (2012)]. The effect of the presence of resonances in the one-photon spectrum on photoionization delay measurements is studied.

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“…First, the electron correlation problem for these atoms and ions is well understood in the case of single photon ionization processes [9][10][11]. This understanding is of great benefit in studying this new process.…”

Section: Electron Correlations Important For Two-photon Ionization Prmentioning

confidence: 99%

“…More specifically, one can cite at least three instances in which electron correlations need to be described: First, quantitative agreement between theoretical MPI generalized cross sections and experiment requires the inclusion of electron correlations. As is known in the theory of single photon ionization processes [9][10][11], neglect of electron correlations can lead to errors of as much as a factor of two. Second, multiphoton photoelectron angular distributions [12] are expected to be even more sensitive to electron correlations due to their dependence on the relative phases of transition amplitudes for alternative photoelectron channels.…”

Section: Introductionmentioning

confidence: 99%

Electron Correlation Effects in Nonresonant Multiphoton Ionization Processes

Starace¹

1987

Phys. Scr.

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The role of electron correlations in nonresonant multiphoton processes of atoms is presented. The evidence for the validity of a lowest order perturbation theory (LOPT) approach for the laser field in the case of nonresonant processes is sketched. The growing consensus for a LOPT interpretation of even the multiply-charged ion spectra obtained with high intensity lasers is reviewed. Finally, a review of those specific electron correlation processes within LOPT that are important for the quantitative prediction of two-photon ionization cross sections is presented and some of their effects on calculated generalized cross sections are exhibited.

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Trends in the theory of atomic photoionization

Cited by 39 publications

References 80 publications

Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation

Recombination-amplitude calculations of noble gases, in both length and acceleration forms, beyond the strong-field approximation

Multiconfigurational Hartree-Fock close-coupling ansatz: Application to the argon photoionization cross section and delays

Electron Correlation Effects in Nonresonant Multiphoton Ionization Processes

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