Role of L -shell single and double core-hole production and decay in m -fold ( 1≤m≤6 ) photoionization of the

A. Müller

¹

,

M. Martins

²

,

A. Borovik

³

et al.

Abstract

Multiple ionization of the Ar + (3s 2 3p 5 ) ion by a single photon has been investigated in the photonenergy range 250-1800 eV employing the photon-ion merged-beams technique. Absolute partial cross sections were measured for all Ar (1+m)+ product-ion channels with 1 ≤ m ≤ 6 covering a size range from several tens of Mb down to a few b. Narrow 2p-subshell excitation resonances were observed in all channels up to quadruple ionization at a photon-energy bandwidth of 52 meV. Double excitations involving a 2p and a 3s or 3p electron were also studied at high resolution and the measurements of the broad 2s excitation resonances directly showed their natural widths. Contributions of direct photo double ionization (PDI) to the production of the highest final Ar ion charge states are revealed, with PDI of the 2s subshell being mainly responsible for the production of Ar 7+ . The experiment made use of the PIPE setup installed at beamline P04 of the PETRA III synchrotron light source of DESY in Hamburg. The measurements were supported by theoretical calculations to identify the main contributions to the observed cross sections. Comparisons of theory and experiment show remarkable agreement but also hint to additional ionization mechanisms that are not considered in the theoretical models such as core ionization accompanied by excitations with subsequent Auger decays leading to net m-fold ionization with m ≥ 4.

Near K-edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

“…Similar to our previous work on L-shell ionization of Fe + , Fe 2+ , Fe 3+ , and Ar + ions (Schippers et al 2017;Beerwerth et al 2019;Müller et al 2021;Schippers et al 2021), we have investigated ionization of silicon ions in different charge states. Here, we present experimental and theoretical data for m-fold photoionization of Si q+ ions with primary charge state q leading to the production of Si r+ ions with product charge state r = q + m n…”

Multiple photodetachment of silicon anions via K -shell excitation and ionization

“…Moreover, the current cascade model does not predict any ions in the q ≥ 6 channels. More accurate predictions for the higher production charge states will also require the incorporation of simultaneous double-detachment processes, either during the initial detachment and/or the subsequent decay (see, e.g., [36,37]).…”

Near K-Edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions

“…Similar to our previous work on L-shell ionization of Fe + , Fe 2+ , Fe 3+ and Ar + ions (Schippers et al 2017;Beerwerth et al 2019;Schippers et al 2021;Müller et al 2021), we have investigated ionization of silicon ions in different charge states. Here, we present experimental and theoretical data for m-fold photoionization of Si q+ ions with primary charge state q leading to the production of Si r+ ions with product charge-state r = q + m hν + Si q+ → Si r+ + me − .…”