Inner-shell photodetachment from ${\mathrm{Ru}}^{\ensuremath{-}}$

Inner-shell photodetachment from ${Ru}^{-}$

I. Dumitriu, R. C. Bilodeau, T. W. Gorczyca, C. W. Walter, N. D. Gibson, Z. D. Pešić, D. Rolles, and N. Berrah

Phys. Rev. A 82, 043434 – Published 26 October 2010

Abstract

Inner-shell photodetachment from ${Ru}^{-}$ was studied near and above the $4 p$ excitation region, 29-to-91-eV photon energy range, using a merged ion-photon-beam technique. The absolute photodetachment cross sections of ${Ru}^{-}$ ( $[Kr] 4 d^{7} 5 s^{2}$ ) leading to ${Ru}^{+}$ , ${Ru}^{2 +}$ , and ${Ru}^{3 +}$ ion production were measured. In the near-threshold region, a Wigner $s$ -wave law, including estimated postcollision interaction effects, locates the $4 p_{3 / 2}$ detachment threshold between 40.10 and 40.27 eV. Additionally, the ${Ru}^{2 +}$ product spectrum provides evidence for simultaneous two-electron photodetachment (likely to the ${Ru}^{+}$ $4 p^{5} 4 d^{6} 5 s^{2}$ state) located near 49 eV. Resonance effects are observed due to interference between transitions of the $4 p$ electrons to the quasibound $4 p^{5} 4 d^{8} 5 s^{2}$ states and the $4 d \to ɛ f$ continuum. Despite the large number of possible terms resulting from the ${Ru}^{-}$ $4 d$ open shell, the cross section obtained from a 51-state $LS$ -coupled $R$ -matrix calculation agrees qualitatively well with the experimental data.

Received 25 July 2010

DOI:https://doi.org/10.1103/PhysRevA.82.043434

Authors & Affiliations

I. Dumitriu^1,*, R. C. Bilodeau^1,2, T. W. Gorczyca¹, C. W. Walter³, N. D. Gibson³, Z. D. Pešić^1,2,†, D. Rolles^1,2,‡, and N. Berrah¹

¹Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008, USA
²Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
³Department of Physics and Astronomy, Denison University, Granville, Ohio 43023, USA

^*Present address: Department of Physics, Gustavus Adolphus College, St. Peter, MN 56082.
^†Present address: Diamond Light Source, Harwell Science and Innovation Campus Didcot, OX11 0DE, United Kingdom.
^‡Present address: Max Planck Advanced Study Group, Center for Free Electron Laser.

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand

Issue

Vol. 82, Iss. 4 — October 2010

Reuse & Permissions

Access Options

Author publication services for translation and copyediting assistance advertisement

Images

Figure 1
High-resolution (100 meV) measured photodetachment cross section for ${Ru}^{+}$ , ${Ru}^{2 +}$ , and ${Ru}^{3 +}$ from ${Ru}^{-}$ . The cross-section scale was established by making absolute measurements (denoted by solid circles) at the three energies shown. Solid curves are the data smoothed over several data points and are included to help guide the eye. For clarity of presentation, the cross section has been multiplied by a factor of 5 for ${Ru}^{2 +}$ and 100 for ${Ru}^{3 +}$ .Reuse & Permissions
Figure 2
Energy-level diagram (to scale) showing ground [9, 24, 25] and some relevant core excited states of ${Ru}^{-}$ , Ru, ${Ru}^{+}$ , ${Ru}^{2 +}$ , and ${Ru}^{3 +}$ , relative to the ground state of ${Ru}^{-}$ [15] (the $4 s$ detachment threshold is estimated from [47]). Included is a preliminary assignment of $4 p^{5} 4 d^{6} 5 s^{2}$ for the core-excited state responsible for the two-electron detachment threshold discussed in Sec. 3c. For clarity of presentation, fine-structure states are not shown. An asterisk ( $^{*}$ ) indicates that the level energy is obtained from this work. The very broad “giant” ${Ru}^{-}$ $4 p^{5} 4 d^{8} 5 s^{2}$ resonant excitations observed in this work are indicated as a range of energies (depicted by a box) around the $4 p$ detachment threshold based on the measured and calculated theoretical spectra. The arrows indicate channels leading to the main structures described herein.Reuse & Permissions
Figure 3
Total photodetachment cross section from 51-state $LS$ -coupled $R$ -matrix calculation (Th $_{tot}$ ). The partial cross section for 36 autoionizing states is also shown (Th $_{auto}$ , magnified by a factor of 4 for clarity of presentation). The measured ${Ru}^{+}$ spectrum is plotted for comparison (the curve is five-point smoothed and magnified by a factor of 4).Reuse & Permissions
Figure 4
Comparison of theory with experiment. Experimental curves are for ${Ru}^{+}$ and the sum of all detected ionic products, as labeled (curves are smoothed over five data points to reduce statistical scatter). The sum of the 36 predicted autodetaching states (Th $_{auto}$ ) is observed to be lacking the resonant enhancement see in the experiment. Including the 42 highest-lying states (Th $_{42}$ ) recovers the structure, but has a cross section approximately a factor of 2 too large.Reuse & Permissions
Figure 5
Comparison of the measured ${Ru}^{2 +}$ spectrum with the calculated cross section including only $4 p$ core-hole states (Th $_{4 p}$ ). The theory curve has been reduced by a factor of 10, to account for the low branching decay leading to ${Ru}^{2 +}$ and shifted up by 0.2 Mb, to estimate the small photodetachment background observed below the $4 p$ threshold.Reuse & Permissions
Figure 6
High-resolution (30 meV) photodetachment cross section of ${Ru}^{-}$ leading to ${Ru}^{+}$ and ${Ru}^{2 +}$ measured near the $4 p$ threshold. The open circles are the experimental data. The solid curve is a Wigner $s$ profile fit to the data with inclusion of PCI effects, assuming an Auger width of 40 meV. The dotted curve is a Wigner $s$ -wave law obtained from the fit with the PCI effects removed. The dashed curve represents the linear background included in the fit.Reuse & Permissions

Physical Review A

covering atomic, molecular, and optical physics and quantum information

Inner-shell photodetachment from ${Ru}^{-}$

I. Dumitriu, R. C. Bilodeau, T. W. Gorczyca, C. W. Walter, N. D. Gibson, Z. D. Pešić, D. Rolles, and N. Berrah

Phys. Rev. A 82, 043434 – Published 26 October 2010

Abstract

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Physical Review A

covering atomic, molecular, and optical physics and quantum information

Inner-shell photodetachment from Ru−

I. Dumitriu, R. C. Bilodeau, T. W. Gorczyca, C. W. Walter, N. D. Gibson, Z. D. Pešić, D. Rolles, and N. Berrah

Phys. Rev. A 82, 043434 – Published 26 October 2010

Abstract

Authors & Affiliations

Article Text (Subscription Required)

References (Subscription Required)

Issue

Access Options

Authorization Required

Other Options

Download & Share

Images

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Log In

Search

Article Lookup

Paste a citation or DOI

Enter a citation

Inner-shell photodetachment from ${Ru}^{-}$