Compact XFEL and AMO sciences: SACLA and SCSS

Yabashi, Makina; Tanaka, Hitoshi; Tanaka, Takashi; Tomizawa, H.; Togashi, Tadashi; Nagasono, Mitsuru; Ishikawa, Tetsuya; Harries, James; Hikosaka, Y.; Hishikawa, Akiyoshi; Nagaya, K.; Saitô, Norio; Shigemasa, E.; Yamanouchi, Kaoru; Ueda, Kiyoshi

doi:10.1088/0953-4075/46/16/164001

Cited by 90 publications

(69 citation statements)

References 101 publications

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“…A series of decay processes, a socalled decay cascade, can occur if the hole is formed in a deep inner shell [1][2][3][4][5]. The interaction with x rays becomes rather complex when the sample is exposed to the unprecedentedly high fluence generated by x-ray free-electron lasers (XFELs) [6][7][8][9]. Beyond the one-photon saturation fluence, which is the inverse of the single-photon ionization cross section [10], a single atom can absorb more than one photon sequentially after or during decay cascades, and then it becomes a highly charged ion.…”

Section: Introductionmentioning

confidence: 99%

Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms

2017

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In this paper, we theoretically study x-ray multiphoton ionization dynamics of heavy atoms taking into account relativistic and resonance effects. When an atom is exposed to an intense x-ray pulse generated by an x-ray free-electron laser (XFEL), it is ionized to a highly charged ion via a sequence of single-photon ionization and accompanying relaxation processes, and its final charge state is limited by the last ionic state that can be ionized by a single-photon ionization. If x-ray multiphoton ionization involves deep inner-shell electrons in heavy atoms, energy shifts by relativistic effects play an important role in ionization dynamics, as pointed out in Phys. Rev. Lett. 110, 173005 (2013). On the other hand, if the x-ray beam has a broad energy bandwidth, the high-intensity x-ray pulse can drive resonant photoexcitations for a broad range of ionic states and ionize even beyond the direct one-photon ionization limit, as first proposed in Nat. Photon. 6, 858 (2012). To investigate both relativistic and resonance effects, we extend the XATOM toolkit to incorporate relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics calculations. Charge-state distributions are calculated for Xe atoms interacting with intense XFEL pulses at a photon energy of 1.5 keV and 5.5 keV, respectively. For both photon energies, we demonstrate that the role of resonant excitations in ionization dynamics is altered due to significant shifts of orbital energy levels by relativistic effects. Therefore, it is necessary to take into account both effects to accurately simulate multiphoton multiple ionization dynamics at high x-ray intensity.

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Section: Introductionmentioning

confidence: 99%

Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms

2017

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“…In the last decade, free-electron laser facilities operating in the XUV and X-ray regimes have become available for scientific investigations [1][2][3]. These facilities have opened up the research area of laser-matter interactions in intense high-frequency fields.…”

Section: Introductionmentioning

confidence: 99%

Time-dependentR-matrix theory applied to two-photon double ionization of He

Hart

2014

Phys. Rev. A

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We introduce a time-dependent R-matrix theory generalised to describe double ionization processes. The method is used to investigate two-photon double ionization of He by intense XUV laser radiation. We combine a detailed B-spline-based wavefunction description in a extended inner region with a single-electron outer region containing channels representing both single ionization and double ionization. A comparison of wavefunction densities for different box sizes demonstrates that the flow between the two regions is described with excellent accuracy. The obtained two-photon double ionization cross sections are in excellent agreement with other cross sections available. Compared to calculations fully contained within a finite inner region, the present calculations can be propagated over the time it takes the slowest electron to reach the boundary.PACS numbers: 32.80. Rm, 32.80.Fb

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“…With the advent of free-electron lasers operating at high photon energies [4][5][6], the interplay between EUV photons and IR photons in the photoionization process [7] can give valuable information about the time delay between the EUV and the IR pulse.…”

Section: Introductionmentioning

confidence: 99%

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

Rey¹,

Hart²

2014

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

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We present R-Matrix with time dependence (RMT) calculations for the photoionization of helium irradiated by an EUV laser pulse and an overlapping IR pulse with an emphasis on the anisotropy parameters of the sidebands generated by the dressing laser field. We investigate how these parameters depend on the amount of atomic structure included in the theoretical model for two-photon ionization. To verify the accuracy of the RMT approach, our theoretical results are compared with experiment.PACS numbers: 31.15.A-,32.80.Rm

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Compact XFEL and AMO sciences: SACLA and SCSS

Cited by 90 publications

References 101 publications

Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms

Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms

Time-dependentR-matrix theory applied to two-photon double ionization of He

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

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