Ultrafast photoionization dynamics at high laser intensities in the xuv regime

Journal Article · Sat Oct 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.84.043431· OSTI ID:22095388

Kaiser, B.; Vagov, A.; Axt, V. M.; Pietsch, U. ^[1]

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1. Institut fuer Theoretische Physik III, Universitaet Bayreuth, D-95440 Bayreuth (Germany)

We study the ionization dynamics in the soft-x-ray regime for high intensities and short pulses for excitations near the ionization threshold. Using a one-dimensional helium atom model, we compare exact numerical solutions with time-dependent Hartree-Fock results in order to identify the role of electron-electron correlations. At moderate intensities but still in the x-ray and short-pulse regime, we find that the Hartree-Fock theory reproduces well the dynamics of the ground-state occupation, while at high intensities strong correlation effects occur for excitations close to the threshold. From their characteristic momentum distributions, we can identify contributions to the double ionization from sequential three-photon and nonsequential or sequential two-photon processes. At elevated intensities these contributions deviate from their usual intensity scaling due to saturation effects, even though the total double-ionization probability stays below 10%. Furthermore, analysis of the time evolution of the momentum distribution reveals signatures of the energy-time uncertainty which indicate a coherent regime of the dynamics.

• OSTI ID: 22095388
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 84; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMS
ELECTRON CORRELATION
ELECTRONS
EXCITATION
EXTREME ULTRAVIOLET RADIATION
GROUND STATES
HARTREE-FOCK METHOD
HELIUM
LASERS
MULTI-PHOTON PROCESSES
NUMERICAL SOLUTION
ONE-DIMENSIONAL CALCULATIONS
PHOTOIONIZATION
PHOTONS
PULSES
SOFT X RADIATION
TIME DEPENDENCE