Valence-shell single photoionization of Kr${}^{+}$ ions: Experiment and theory

Valence-shell single photoionization of Kr $^{+}$ ions: Experiment and theory

G. Hinojosa, A. M. Covington, G. A. Alna'Washi, M. Lu, R. A. Phaneuf, M. M. Sant'Anna, C. Cisneros, I. Álvarez, A. Aguilar, A. L. D. Kilcoyne, A. S. Schlachter, C. P. Ballance, and B. M. McLaughlin

Phys. Rev. A 86, 063402 – Published 5 December 2012

Abstract

Photoionization of Kr $^{+}$ ions was studied in the energy range from 23.3 to 39.0 eV at a photon energy resolution of 7.5 meV. Absolute measurements were performed by merging beams of Kr $^{+}$ ions and of monochromatized synchrotron undulator radiation. Photoionization (PI) of this Br-like ion is characterized by multiple Rydberg series of autoionizing resonances superimposed on a direct PI continuum. Resonance features observed in the experimental spectra are spectroscopically assigned and their energies and quantum defects tabulated. The high-resolution cross-section measurements are benchmarked against state-of-the-art theoretical cross-section calculations from the Dirac-Coulomb $R$ -matrix method [J. Phys. B 45, 085701 (2012)].

Received 11 September 2012

DOI:https://doi.org/10.1103/PhysRevA.86.063402

Authors & Affiliations

G. Hinojosa^*, A. M. Covington, G. A. Alna'Washi^†, M. Lu, and R. A. Phaneuf

Department of Physics, University of Nevada, Reno, Nevada 89557-0220, USA

M. M. Sant'Anna

Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528 – CEP, 21941-972 Rio de Janeiro RJ, Brazil

C. Cisneros and I. Álvarez

Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Apartado Postal 48-3, Cuernavaca 62210, Morelos, México

A. Aguilar, A. L. D. Kilcoyne, and A. S. Schlachter

Advanced Light Source, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA

C. P. Ballance

Department of Physics, 206 Allison Laboratory, Auburn University, Auburn, Alabama 36849-5311, USA

B. M. McLaughlin^‡

Institute for Theoretical Atomic and Molecular Physics, Harvard Smithsonian Center for Astrophysics, 60 Garden Street, MS-14, Cambridge, Massachusetts 02138, USA

^*Present address: Instituto de Ciencias Físicas, Universidad NacionalAutónoma de México, Apartado Postal 48-3, Cuernavaca 62210, Morelos, México; hinojosa@fis.unam.mx
^†Present address: Department of Physics, The Hashemite University, Zarqa 13115, Jordan; alnawashi@hu.edu.jo
^‡Present address: Centre for Theoretical Atomic, Molecular and Optical Physics (CTAMOP), School of Mathematics and Physics, The David Bates Building, 7 College Park, Queen's University of Belfast, Belfast BT7 1NN, United Kingdom; b.mclaughlin@qub.ac.uk

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Vol. 86, Iss. 6 — December 2012

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Images

Figure 1
An overview of single photoionization cross-section measurements from the ALS of Kr $^{+}$ ions as a function of the photon energy. The data were taken with a nominal energy resolution of 7.5 meV. Two assigned Rydberg series are indicated as vertical lines grouped by horizontal lines. The corresponding series limits $E_{\infty}$ of Eq. (4) for each series are indicated by vertical-dashed lines in the end of the line groups. Labels correspond to two final states generated from initial ground state Kr $^{+}$ ( $^{2}$ $P$ $_{3 / 2}^{o}$ ). Identified resonance features of this graphic are tabulated in Table . The inset shows the low-energy region on an expanded energy scale. Assignments at lower energies are shown in Fig. 3 which is a smaller range of the same spectrum. The ALS absolute measurements given in Table are shown as open circles.Reuse & Permissions
Figure 2
Comparison of present absolute cross-section measurements for single photoionization of Kr $^{+}$ taken at 7.5-meV resolution at ALS with absolute measurements of Bizau et al. [3] measured at ASTRID with a resolution of 30 meV. The ALS absolute measurements are shown as open circles.Reuse & Permissions
Figure 3
Single photoionization measurements from the ALS of Kr $^{+}$ ions as a function of the photon energy measured with a nominal energy resolution of 7.5 meV. The assigned Rydberg series are indicated as vertical lines grouped by horizontal or inclined lines. The corresponding series limits $E_{\infty}$ of Eq. (4) for each series are indicated by a vertical-dashed line in the end of the line groups. Labels to the left correspond to final states of series generated from initial metastable Kr $^{+}$ ( $^{2}$ $P$ $_{1 / 2}^{o}$ ). Labels to the right correspond to final states of series generated from ground state Kr $^{+}$ ( $^{2}$ $P$ $_{3 / 2}^{o}$ ). The first value of $n$ for each series is displayed close to its corresponding vertical line in each group. Gaussian fit centers to the peaks are tabulated in Tables . The inset shows the low-energy region on an expanded energy scale.Reuse & Permissions
Figure 4
An overview of measurements for the absolute single photoionization measurements of Kr $^{+}$ ions as a function of the photon energy measured with theoretical estimates for cross sections. The ASTRID and SOLEIL measurements are at a nominal energy resolution of 30 meV. Theoretical results were obtained from a Dirac-Coulomb $R$ -matrix method, convoluted with the appropriate Gaussian of full width at half maximum (FWHM) and a statistical admixture of 2/3 ground and 1/3 metastable states.Reuse & Permissions
Figure 5
An overview of measurements for the absolute single photoionization measurements of Kr $^{+}$ ions as a function of the photon energy measured with theoretical estimates for cross sections. The ALS measurements are at a nominal energy resolution of 7.5 meV and normalized to the ASTRID and SOLEIL measurements at 26.5025 eV. Theoretical results were obtained from a Dirac-Coulomb $R$ -matrix method, convoluted with the appropriate Gaussian of FWHM and a statistical admixture of 2/3 ground and 1/3 metastable states.Reuse & Permissions

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