Impact of intense laser pulses on the autoionization dynamics of the 
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 doubly excited state of He

Artemyev, A. N.; Cederbaum, Lorenz S.; Demekhin, Ph. V.

doi:10.1103/physreva.96.033410

Cited by 22 publications

(19 citation statements)

References 67 publications

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“…2. We note that changes of the resonance profile have also been predicted by recent theoretical calculations [25][26][27], whereas here we identify the mechanism of dressing-induced phase shifts on a timescale shorter than the autoionization lifetime, which we believe is the main reason for twisting the Fano line into a more symmetric shape with higher XUV photon fluence.…”

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Strong-Field Extreme-Ultraviolet Dressing of Atomic Double Excitation

et al. 2019

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We report on the experimental observation of strong-field dressing of an autoionizing two-electron state in helium with intense extreme-ultraviolet laser pulses from a freeelectron laser. The asymmetric Fano line shape of this transition is spectrally resolved, and we observe modifications of the resonance asymmetry structure for increasing free-electron-laser pulse energy on the order of few tens of µJ. A quantum-mechanical calculation of the time-dependent dipole response of this autoionizing state, driven by classical extreme-ultraviolet (XUV) electric fields, reveals a direct link between strongfield-induced energy and phase shifts of the doubly excited state and the Fano line-shape asymmetry. The experimental results obtained at the Free-Electron Laser in Hamburg (FLASH) thus correspond to transient energy shifts on the order of few meV, induced by strong XUV fields. These results open up a new way of performing non-perturbative XUV nonlinear optics for the light-matter interaction of resonant electronic transitions in atoms at short wavelengths.Quantum mechanics provides a consistent description of the structure and dynamics of atoms, the constituents of our macroscopic world. In particular, it describes how bound excited states in atoms are formed through the Coulomb interaction of the positively charged nucleus and the negatively charged electrons. With the obvious exception of the ground state, such states possess a finite lifetime, with singly excited states decaying through photon emission via the interaction with the radiation field. For two-electron excitations of neutral atoms, the Coulomb interaction between the electrons is much more effective such that at least one electron will eventually be ionized, which typically marks the leading contribution to the decay of the excited state for the case of light atoms. Thus ionization is a fundamentally important and very basic effect that accompanies the physics of multi-electron excitations in atoms [1]. An interesting situation arises if the interaction of such states with the radiation field is significantly increased which nowadays can be achieved by using extreme ultraviolet (XUV) or x-ray light sources. In addition, the properties of these radiation fields can often be well controlled, thus providing a unique toolbox for exploring the dynamics of excited states, e.g., by performing time-resolved investigations with lab-based attosecond high-order harmonic generation (HHG) sources [2,3], or facility-based femtosecond XUV/x-ray freeelectron lasers (FELs) [4,5]. The latter deliver particularly high intensities for XUV/x-ray nonlinear optics [6] with ultrafast time resolution and site-specific core-level access [7], and nowadays even approach the attosecond regime [8].The helium atom consists of two electrons bound to a nucleus, representing the ideal case of a Coulombic three-body system, which serves as a benchmark for developing a theoretical description [1,9,10] and most importantly also for controlling the dynamics of two bound electrons with stron...

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confidence: 84%

Strong-Field Extreme-Ultraviolet Dressing of Atomic Double Excitation

et al. 2019

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“…The time-dependent electron wave packets were propagated using the short-iterative Lanczos method [32]. Electrons with very high kinetic energies were absorbed by a mask function at the end of the radial grid [26,27].…”

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confidence: 99%

Photoelectron circular dichroism in the multiphoton ionization by short laser pulses. III. Photoionization of fenchone in different regimes

Müller

Kutscher

Artemyev

et al. 2020

The Journal of Chemical Physics

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Photoelectron circular dichroism (PECD) in different regimes of multiphoton ionization of fenchone is studied theoretically using the time-dependent single center method. In particular, we investigate the chiral response to the one-color multiphoton or strong-field ionization by circularly polarized 400 and 814 nm optical laser pulses or 1850 nm infrared pulse. In addition, the broadband ionization by short coherent circularly polarized 413-1240 nm spanning pulse is considered.Finally, the two-color ionization by the phase-locked 400 and 800 nm pulses, which are linearly polarized in mutually-orthogonal directions, is investigated. The present computational results on the one-color multiphoton ionization of fenchone are in agreement with the available experimental data. For the ionization of fenchone by broadband and bichromatic pulses, the present theoretical study predicts substantial multiphoton PECDs.

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“…A mask function [45,46] at the end of the grid was introduced to avoid reflections of very fast electrons from the grid boundary. were covered with the steps of ∆α = ∆β = 0.1 π.…”

Section: Computational Detailsmentioning

confidence: 99%

Photoelectron circular dichroism in the multiphoton ionization by short laser pulses. II. Three- and four-photon ionization of fenchone and camphor

Müller

Artemyev

Demekhin

2018

The Journal of Chemical Physics

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Angle-resolved multiphoton ionization of fenchone and camphor by short intense laser pulses is computed by the time-dependent single center method. Thereby, the photoelectron circular dichroism (PECD) in the three-photon resonance enhanced ionization and four-photon above-threshold ionization of these molecules is investigated in detail. The computational results are in satisfactory agreement with the available experimental data, measured for randomly oriented fenchone and camphor molecules at different wavelengths of the exciting pulses. We predict a significant enhancement of the multiphoton PECD for uniaxially oriented fenchone and camphor.

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Impact of intense laser pulses on the autoionization dynamics of the 2s2p doubly excited state of He

Cited by 22 publications

References 67 publications

Strong-Field Extreme-Ultraviolet Dressing of Atomic Double Excitation

Strong-Field Extreme-Ultraviolet Dressing of Atomic Double Excitation

Photoelectron circular dichroism in the multiphoton ionization by short laser pulses. III. Photoionization of fenchone in different regimes

Photoelectron circular dichroism in the multiphoton ionization by short laser pulses. II. Three- and four-photon ionization of fenchone and camphor

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