Above-threshold double ionization of helium with attosecond intense soft x-ray pulses

Journal Article · Fri Jul 15 04:00:00 EDT 2005 · Physical Review. A

DOI:https://doi.org/10.1103/PhysRevA.72.013407· OSTI ID:20718388

Ishikawa, Kenichi L; Midorikawa, Katsumi ^[1]

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1. Department of Quantum Engineering and Systems Science, Graduate School of Engineering, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8656 (Japan)

We theoretically study a process in which helium is doubly ionized by absorbing two soft x-ray (91.45 eV) photons from attosecond, intense high-order harmonic sources. We directly solve the time-dependent Schroedinger equation and obtain electron energy distribution in the double continuum. Our results show that between the two peaks in electron energy spectra, expected for usual sequential ionization, an additional component (anomalous component) is present. The total two photon above-threshold double ionization yield including the anomalous component is explained by sequential processes: the two electrons are ejected one by one, absorbing a single photon each. This observation rejects the intuition that nonsequential double ionization would be responsible for the anomalous component. With the help of simple semiclassical stochastic models, we discuss two possible origins of the anomalous component, namely, postionization energy exchange and second ionization during core relaxation, of which the latter is more plausible: the ionization interval is so short that the second electron is ejected while the two electrons are still exchanging energy.

• OSTI ID: 20718388
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 1 Vol. 72; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

74 ATOMIC AND MOLECULAR PHYSICS
ATOMS
ELECTRONS
ENERGY SPECTRA
ENERGY TRANSFER
EV RANGE
HELIUM
MULTI-PHOTON PROCESSES
PHOTOIONIZATION
PHOTON-ATOM COLLISIONS
PHOTONS
PULSES
RELAXATION
SCHROEDINGER EQUATION
SEMICLASSICAL APPROXIMATION
SOFT X RADIATION
STOCHASTIC PROCESSES
TIME DEPENDENCE