One-step double autoionization into the double-photoionization continuum

Wehlitz, R.; Huang, Ming-Tie; Berrington, K A; Nakazaki, Shinobu; Azuma, Y.

doi:10.1103/physreva.60.r17

Cited by 30 publications

(15 citation statements)

References 23 publications

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“…This is to be contrasted with the case of double photoionization of helium, for which there is no core of atomic electrons left behind and therefore no such Feshbach resonance mechanism. Note also that related processes have been seen in other systems [16][17][18].…”

Section: General Considerationssupporting

confidence: 63%

Double photoionization of atomic oxygen: Feshbach resonances in the two-electron continuum

Gorczyca¹,

Ballance²,

Manson³

et al. 2021

Phys. Scr.

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We describe a joint experimental and theoretical investigation on oxygen double photoionization—the emission of two electrons from atomic oxygen following single photon absorption. High-resolution experimental measurements were performed at the Advanced Light Source, revealing sharp resonance structure superimposed on the more familiar Wannier-like, nearly-linear background. These resonance features are attributed to ionization-plus-excitation Feshbach resonances embedded in the double ionization continuum, doubly-excited states that lie above the double-ionization threshold. Such features are absent in the double photoionization cross section of He, or other quasi-two-electron systems, for which the doubly-ionized atomic core remains inert. For a corresponding theoretical analysis, the R-matrix with pseudostates (RMPS) method was invoked by calculating final-state, two-electron resonances-plus-continua wavefunctions and corresponding single-photon absorption cross sections. Overall agreement is found in the direct, background double photoionization cross section. However, the RMPS method, using a small basis due to practical computational limitations, was unable to reproduce quantitatively the smooth background or the sharper resonance features observed in the measurements, showing instead large-scale oscillations about the experimental background, and characteristic pseudoresonance jitter, associated with an insufficient convergence of the pseudostate representation to the true two-electron infinite series of Feshbach resonances embedded in the two-electron continuum. The prominent resonance structure observed highlights the need to consider multiple excitation processes in atoms more complex than He or quasi-two-electron systems.

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Section: General Considerationssupporting

confidence: 63%

Double photoionization of atomic oxygen: Feshbach resonances in the two-electron continuum

Gorczyca¹,

Ballance²,

Manson³

et al. 2021

Phys. Scr.

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show abstract

“…The indirect double ionization processes can be divided basically into a (I) one-step process and (II) two-step process via an intermediate state of M + . The one-step process (I) has been expressed in different denominations by different authors [49][50][51][52][53]. In this paper, the one-step process (I) will be expressed as one-step double autoionization [49] or the resonant double Auger process depending on whether the peak profile in the M 2+ channel is of a Beutler-Fano type or Lorentzian type.…”

Section: Formation Of M 2+ Ions At Photon Energies Below the 3p Ioniz...mentioning

confidence: 99%

Photoion-yield study of the 3p–3d giant resonance excitation region of isolated Cr, Mn and Fe atoms

Osawa

Kawajiri

Suzuki

et al. 2012

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

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Using the charge-separated photoion-yield method combined with monochromatized synchrotron radiation, single (M+) and double (M2+) photoionization spectra in the 3p excitation region were observed for isolated atoms M = Cr, Mn and Fe. The relaxation processes of excited states to double ionization, as well as to single ionization, were considered with the help of existing photoabsorption and photoelectron data and some calculations of highly-excited states of M+ using the atomic code GRASP92. In the 3p→3d giant resonance region before the 3p→n(s, d) Rydberg series starts, the spectral features in the M2+ channel are similar to those in the M+ channel. The ratios M2+/M+ in this region are rather constant accordingly against the photon energy with values 0.045 ± 0.005 for Cr, 0.17 ± 0.03 for Mn and 0.30 ± 0.08 for Fe at the giant resonance. The increase in the M2+/M+ ratio with increasing the atomic number Z can be explained by the increasing contribution of two-step double ionization via highly-excited M+ states. It is expected that, at the 3p→3d giant resonance, the one-step double ionization process occurs within a few per cent of the entire decay.

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“…Nevertheless, resonances in different partial cross sections are expected to show different asymmetries. For example, in a recent experimental measurement of Li photoionization, the resonance profiles of the 2s 2 2p triply excited state in the single and double ionization partial cross sections exhibit q values of different signs [27].…”

mentioning

confidence: 99%

Mirroring Doubly Excited Resonances in Argon

Canton-Rogan

Wills

Gorczyca³

et al. 2000

Phys. Rev. Lett.

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New features are revealed in the low-energy photoionization spectrum of Ar by critically combining high photon resolution and differential photoelectron spectroscopic techniques. Two LS-forbidden doubly excited resonances are seen in the 3p(-1)(3/2, 1/2) partial cross sections which exhibit mirroring profiles, resulting in complete cancellation in the total photoionization cross section, as was predicted by Liu and Starace [Phys. Rev. A 59, R1731 (1999)]. These results demonstrate that a new class of weakly spin-orbit induced, mirroring resonances should be observable in partial, but not in total, collisional cross sections involving atoms, molecules, and solids in general.

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One-step double autoionization into the double-photoionization continuum

Cited by 30 publications

References 23 publications

Double photoionization of atomic oxygen: Feshbach resonances in the two-electron continuum

Double photoionization of atomic oxygen: Feshbach resonances in the two-electron continuum

Photoion-yield study of the 3p–3d giant resonance excitation region of isolated Cr, Mn and Fe atoms

Mirroring Doubly Excited Resonances in Argon

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