Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

Callegari, Carlo; Grum–Grzhimailo, A. N.; Ishikawa, Kenichi L.; Sansone, G.; Ueda, Kiyoshi

doi:10.1016/j.physrep.2020.12.002

Cited by 34 publications

(16 citation statements)

References 417 publications

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“…The advent of high-intensity x-ray free-electron lasers (XFELs) has opened frontiers to study nonlinear ionization processes, such as the two-photon ionization (TPI) [1][2][3]. The TPI is one of the most fundamental nonlinear phenomena in the light-matter interaction process, in which an atom absorbs two photons and emits a photoelectron.…”

Section: Introductionmentioning

confidence: 99%

Relativistic calculations of two-color two-photon K-shell ionization

et al. 2022

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We investigate the two-color two-photon K-shell ionization of neutral atoms based on the relativistic second-order perturbation theory and independent particle approximation. Analytical expressions for the relativistic and nonrelativistic total cross sections are derived in terms of radial transition amplitudes and Stokes parameters. Particular attention is paid especially to how the two-photon ionization total cross section depends on the energy sharing and polarization of the two incident photons. We construct the nonrelativistic expressions of cross section ratios for different polarization combinations of the two incident photons. The numerical results of total cross section and cross section ratios show that the energy sharing of the two incident photons plays an essential role in two-photon K-shell ionization. Particularly, if the energies of the two incident photons are identical, the total cross section and cross section ratios will reach the minimum or maximum value. Moreover, due to the strong screening effects, we find strong deviations of the cross section ratios near the two-photon ionization threshold of the Ne atom. Graphical abstract

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Section: Introductionmentioning

confidence: 99%

Relativistic calculations of two-color two-photon K-shell ionization

et al. 2022

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“…The generation of ultra-bright electron sources is currently demanded in many fields of applications, ranging from high-resolution spectroscopy [ 1 ] to electron diffraction [ 2 ] and electron microscopy [ 3 ]. Laser-driven photocathode radio-frequency injectors are currently employed in particle accelerators to pursue enhanced beam brightness, which in turn grants unprecedented opportunities for material characterization following the dynamics of charge carriers in their natural space and time scales [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Ab Initio Quantum-Mechanical Predictions of Semiconducting Photocathode Materials

Cocchi

Saßnick

2021

Micromachines

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Ab initio quantum–mechanical methods are well-established tools for material characterization and discovery in many technological areas. Recently, state-of-the-art approaches based on density-functional theory and many-body perturbation theory were successfully applied to semiconducting alkali antimonides and tellurides, which are currently employed as photocathodes in particle accelerator facilities. The results of these studies have unveiled the potential of ab initio methods to complement experimental and technical efforts for the development of new, more efficient materials for vacuum electron sources. Concomitantly, these findings have revealed the need for theory to go beyond the status quo in order to face the challenges of modeling such complex systems and their properties in operando conditions. In this review, we summarize recent progress in the application of ab initio many-body methods to investigate photocathode materials, analyzing the merits and the limitations of the standard approaches with respect to the confronted scientific questions. In particular, we emphasize the necessary trade-off between computational accuracy and feasibility that is intrinsic to these studies, and propose possible routes to optimize it. We finally discuss novel schemes for computationally-aided material discovery that are suitable for the development of ultra-bright electron sources toward the incoming era of artificial intelligence.

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“…Changing the relative phase and the strength of harmonics provides a way to control the PADs as it was realized in the ω + 2ω process 30 years ago in the optical domain [16][17][18]. Recently, with the advent of longitudinally coherent free-electron lasers, experimental studies of the coherent control in the ω + 2ω process in the XUV wavelength range became possible and the first such measurements have been done [19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…20.03 0.89|2p 5 3d 3 P − 0.43|2p 5 3d 1 P − 0.12|2p 5 3d 3 D 2p 5 ( 2 P 3/2 )3d[3/2] 20.04 0.27|2p 5 3d 3 P + 0.72|2p 5 3d 1 P − 0.64|2p 5 3d 3 D 2p 5 ( 2 P 1/2 )3d[3/2]20.14 −0.36|2p 5 3d 3 P − 0.54|2p 5 3d 1 P − 0.76|2p 5 3d 3 D 2p 5( 2 P 3/2 )5s[3/2]20.57 −0.62|2p 5 5s 3 P − 0.78|2p 5 5s 1 P 2p 5( 2 P 1/2 )5s[1/2]20.66 −0.76|2p 5 5s 3 P + 0.60|2p 5 5s 1 P2p 5 ( 2 P 3/2 )4d[1/2]20.70 0.87|2p 5 4d 3 P − 0.39|2p 5 4d 1 P − 0.16|2p 5 4d 3 D − −0.20|2p 5 5s 3 P + 0.17|2p 5 5s 1 P 2p 5 ( 2 P 3/2 )4d[3/2] 20.71 0.18|2p 5 4d 3 P + 0.73|2p 5 4d 1 P − 0.66|2p 5 4d 3 D − −0.05|2p 5 5s 3 P + 0.05|2p 5 5s 1 P 2p 5 ( 2 P 1/2 )4d[3/2] 20.81 0.39|2p 5 4d 3 P + 0.57|2p 5 4d 1 P + 0.73|2p 5 4d 3 D 2p 5 ( 2 P 3/2 )6s[3/2] 20.95 0.60|2p 5 6s 3 P + 0.80|2p 5 6s 1 P 2p 5 ( 2 P 3/2 )5d[1/2] 21.01 0.90|2p 5 5d 3 P − 0.40|2p 5 5d 1 P − 0.18|2p 5 5d 3 D 2p 5 ( 2 P 3/2 )5d[3/2] 21.02 0.18|2p 5 5d 3 P + 0.72|2p 5 5d 1 P − 0.67|2p 5 5d 3 D 2p 5 ( 2 P 1/2 )6s[1/2] 21.04 −0.80|2p 5 6s 3 P + 0.60|2p 5 6s 1 P 2p 5 ( 2 P 1/2 )5d[3/2] 21.11 0.40|2p 5 5d 3 P + 0.57|2p 5 5d 1 P + 0.72|2p 5 5d 3 D…”

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confidence: 99%

Symmetry Violation in Bichromatic Ionization by a Free-Electron Laser: Photoelectron Angular Distribution and Spin Polarization

et al. 2021

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A fundamental phenomenon of coherent control is investigated theoretically using the example of neon photoionization by the bichromatic field of a free-electron laser. A system exposed to coherent fields with commensurable frequencies loses some symmetry, which manifests itself in the angular distribution and spin polarization of the electron emission. We predict several such effects, for example, the violation of symmetry with respect to the plane perpendicular to the polarization vector of the second harmonic and the appearance of new components of spin polarization. Furthermore, we predict a very efficient control of spin polarization via manipulation of the phase between the harmonics. Experimental observation of these effects is accessible with modern free-electron lasers operating in the extreme ultraviolet wavelength regime.

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Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers

Cited by 34 publications

References 417 publications

Relativistic calculations of two-color two-photon K-shell ionization

Relativistic calculations of two-color two-photon K-shell ionization

Ab Initio Quantum-Mechanical Predictions of Semiconducting Photocathode Materials

Symmetry Violation in Bichromatic Ionization by a Free-Electron Laser: Photoelectron Angular Distribution and Spin Polarization

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