- Physical Review Journals
All JournalsPhysics Magazine

Physical Review A

Reuse & Permissions

It is not necessary to obtain permission to reuse this article or its components as it is available under the terms of the Creative Commons Attribution 4.0 International license. This license permits unrestricted use, distribution, and reproduction in any medium, provided attribution to the author(s) and the published article's title, journal citation, and DOI are maintained. Please note that some figures may have been included with permission from other third parties. It is your responsibility to obtain the proper permission from the rights holder directly for these figures.

Export citation

Export citation

Choose format for download:

Download Citation
  • Open Access

Laboratory measurements of Ca XIX dielectronic recombination satellites

Filipe Grilo1,*, Marc Botz2, Chintan Shah3,2,4,†, Thomas Pfeifer2, José R. Crespo López-Urrutia2, and Pedro Amaro1,‡

  • *Contact author: f.grilo@campus.fct.unl.pt
  • †Contact author: chintan.shah@mpi-hd.mpg.de
  • ‡Contact author: pdamaro@fct.unl.pt
PDF

Phys. Rev. A 113, 032819 – Published 27 March, 2026

DOI: https://doi.org/10.1103/2x7s-bv7g

Abstract

We report measurements of the astrophysically predominant Kα emission from Ca XIX (He-like ion) and its satellite lines resonantly excited by dielectronic recombination (DR). We achieve an electron-energy resolution of 8 eV in a cryogenic electron beam ion trap, and determine the energies of the exciting electrons and the emitted photons up to the KLN (n≤8) manifold with 0.05 and 0.1% respective uncertainties. For the KLL satellites, energies agree very well with our predictions using the Flexible Atomic Code (fac) and previous state-of-the-art calculations. Our calculations also agree with our experimental direct excitation cross sections for Kα within their 10% uncertainty. We extract DR coefficient rates from our fac calculations and find good agreement with values tabulated in the OPEN-ADAS database. Moreover, we compare fac synthetic spectra, incorporating the DR atomic data benchmarked in the present work, with recent x-ray imaging and spectroscopy mission observations. This comparison highlights the contributions of DR satellites to the Ca xix main lines.

View figure in article

Physics Subject Headings (PhySH)

Article Text

References (91)

  1. R. Giacconi, E. Kellogg, P. Gorenstein, H. Gursky, and H. Tananbaum, An X-ray scan of the galactic plane from UHURU, Astrophys. J. 165, L27 (1971).
  2. J. H. Smith and G. M. Courtier, The Ariel 5 programme, Proc. R. Soc. A 350, 421 (1976).
  3. K. S. Wood, J. F. Meekins, D. J. Yentis, H. W. Smathers, D. P. McNutt, R. D. Bleach, H. Friedman, E. T. Byram, T. A. Chubb, and M. Meidav, The HEAO A-1 X-ray source catalog, Astrophys. J. Suppl. Ser. 56, 507 (1984).
  4. C. R. Canizares, D. P. Huenemoerder, D. S. Davis, D. Dewey, K. A. Flanagan, J. Houck, T. H. Markert, H. L. Marshall, M. L. Schattenburg, N. S. Schulz, M. Wise, J. J. Drake, and N. S. Brickhouse, High-resolution X-ray spectra of capella: Initial results from the Chandra high-energy transmission grating spectrometer, Astrophys. J. 539, L41 (2000).
  5. A. C. Brinkman, C. J. T. Gunsing, J. S. Kaastra, R. L. J. van der Meer, R. Mewe, F. Paerels, A. J. J. Raassen, J. J. van Rooijen, H. Bräuninger, W. Burkert, V. Burwitz, G. Hartner, P. Predehl, J.-U. Ness, J. H. M. M. Schmitt, J. J. Drake, O. Johnson, M. Juda, V. Kashyap, S. S. Murray, et al., First light measurements of capella with the low-energy transmission grating spectrometer aboard the Chandra X-Ray Observatory, Astrophys. J. 530, L111 (2000).
  6. J. W. den Herder, A. C. Brinkman, S. M. Kahn, G. Branduardi-Raymont, K. Thomsen, H. Aarts, M. Audard, J. V. Bixler, A. J. den Boggende, J. Cottam, T. Decker, L. Dubbeldam, C. Erd, H. Goulooze, M. Güdel, P. Guttridge, C. J. Hailey, K. Al Janabi, J. S. Kaastra, P. A. J. de Korte, et al., The reflection grating spectrometer on board XMM-Newton, Astron. Astrophys. 365, L7 (2001).
  7. F. B. Paerels and S. M. Kahn, High-resolution X-ray spectroscopy with Chandra and XMM-Newton, Annu. Rev. Astron. Astrophys. 41, 291 (2003).
  8. Y. Ezoe, T. Ohashi, and K. Mitsuda, High-resolution X-ray spectroscopy of astrophysical plasmas with X-ray microcalorimeters, Rev. Mod. Plasma Phys. 5, 4 (2021).
  9. J. R. Peterson, S. M. Kahn, F. B. S. Paerels, J. S. Kaastra, T. Tamura, J. A. M. Bleeker, C. Ferrigno, and J. G. Jernigan, High-resolution X-ray spectroscopic constraints on cooling-flow models for clusters of galaxies, Astrophys. J. 590, 207 (2003).
  10. J.-U. Ness, R. Mewe, J. H. M. M. Schmitt, A. J. J. Raassen, D. Porquet, J. S. Kaastra, R. L. J. van der Meer, V. Burwitz, and P. Predehl, Helium-like triplet density diagnostics, Astron. Astrophys. 367, 282 (2001).
  11. S. Kaspi, W. N. Brandt, I. M. George, H. Netzer, D. M. Crenshaw, J. R. Gabel, F. W. Hamann, M. E. Kaiser, A. Koratkar, S. B. Kraemer, G. A. Kriss, S. Mathur, R. F. Mushotzky, K. Nandra, B. M. Peterson, J. C. Shields, T. J. Turner, and W. Zheng, The ionized gas and nuclear environment in NGC 3783. I. Time-averaged 900 kilosecond Chandra grating spectroscopy, Astrophys. J. 574, 643 (2002).
  12. T. Takahashi, M. Kokubun, K. Mitsuda, R. Kelley, T. Ohashi, F. Aharonian, H. Akamatsu, F. Akimoto, S. Allen, N. Anabuki, et al., in Space Telescopes and Instrumentation 2016: Ultraviolet to Gamma Ray, Proceedings of SPIE, edited by J.-W. A. den Herder, T. Takahashi, and M. Bautz (SPIE, Bellingham, WA, 2016), Vol. 9905, p. 99050U.
  13. A. R. Foster, L. Ji, R. K. Smith, and N. S. Brickhouse, Updated atomic data and calculations for X-ray spectroscopy, Astrophys. J. 756, 128 (2012).
  14. J. S. Kaastra, R. Mewe, and H. Nieuwenhuijzen, SPEX: A new code for spectral analysis of X and UV spectra, 11th Colloquium on UV and X-ray Spectroscopy of Astrophysical and Laboratory Plasmas (Universal Academy Press, Inc. Tokyo, Japan, 1996), pp. 411–414.
  15. P. R. Young, K. P. Dere, E. Landi, G. D. Zanna, and H. E. Mason, The chianti atomic database, J. Phys. B 49, 074009 (2016).
  16. F. Aharonian, H. Akamatsu, F. Akimoto, S. W. Allen, L. Angelini, M. Audard, H. Awaki, M. Axelsson, A. Bamba, M. W. Bautz, et al., Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi, Publ. Astron. Soc. Jpn. 70, 12 (2018).
  17. M. Audard et al. (XRISM Collaboration), The XRISM first-light observation: Velocity structure and thermal properties of the supernova remnant N 132D, Publ. Astron. Soc. Jpn. 76, 1186 (2024).
  18. M. Audard et al. (XRISM Collaboration), Kinematic evidence for bipolar ejecta flows in the galactic supernova remnant W49B, Astrophys. J. Lett. 988, L58 (2025).
  19. M. Audard et al. (XRISM Collaboration), The bulk motion of gas in the core of the Centaurus galaxy cluster, Nature (London) 638, 365 (2025).
  20. M. Audard et al. (XRISM Collaboration), XRISM spectroscopy of the Fe Kα emission line in the seyfert active galactic nucleus NGC 4151 reveals the disk, broad-line region, and torus, Astrophys. J. Lett. 973, L25 (2024).
  21. M. Audard et al. (XRISM Collaboration), The XRISM/resolve view of the Fe K region of Cyg X-3, Astrophys. J. Lett. 977, L34 (2024).
  22. M. Audard et al. (XRISM Collaboration), Overionized plasma in the supernova remnant Sagittarius A East anchored by XRISM observations, Publ. Astron. Soc. Jpn. 77, L1 (2025).
  23. A. H. Gabriel and C. Jordan, Interpretation of solar helium-like ion line intensities, Mon. Not. R. Astron. Soc. 145, 241 (1969).
  24. H. S. W. Massey and D. R. Bates, The properties of neutral and ionized atomic oxygen and their influence on the upper atmosphere, Rep. Prog. Phys. 9, 62 (1942).
  25. A. Burgess, Delectronic recombination and the temperature of the solar corona, Astrophys. J. 139, 776 (1964).
  26. T. Kato, U. I. Safronova, A. S. Shlyaptseva, M. Cornille, J. Dubau, and J. Nilsen, Comparison of satellite spectra for H-like Fe and He-like Fe, Ca, and S calculated by three different methods, At. Data Nucl. Data Tables 67, 225 (1997).
  27. S. Sardar, S.-X. Wang, and L.-F. Zhu, KLL dielectronic satellite spectra from the photorecombination of He-like Fe and Ni ions, Astrophys. J. 869, 128 (2018).
  28. V. A. Yerokhin and A. Surzhykov, Energy levels of core-excited 1s2l2l′ states in lithium-like ions: Argon to uranium, J. Phys. Chem. Ref. Data 47, 023105 (2018).
  29. J. L. Rui, L. Y. Xie, Y. L. Ma, and C. Z. Dong, Theoretical study of dielectronic recombination and electron-impact excitation for helium-like isoelectronic sequence, Eur. Phys. J. D 77, 174 (2023).
  30. D. A. Knapp, R. E. Marrs, M. A. Levine, C. L. Bennett, M. H. Chen, J. R. Henderson, M. B. Schneider, and J. H. Scofield, Dielectronic recombination of heliumlike nickel, Phys. Rev. Lett. 62, 2104 (1989).
  31. Y. Hahn and R. Bellantone, Dielectronic recombination for metastable O vii and C v ions, Phys. Rev. A 40, 6117 (1989).
  32. L. H. Andersen, P. Hvelplund, H. Knudsen, and P. Kvistgaard, State-selective dielectronic-recombination measurements for He-like oxygen ions in an electron cooler, Phys. Rev. Lett. 62, 2656 (1989).
  33. P. Beiersdorfer, A. L. Osterheld, M. H. Chen, J. R. Henderson, D. A. Knapp, M. A. Levine, R. E. Marrs, K. J. Reed, M. B. Schneider, and D. A. Vogel, Indirect X-ray line formation processes in highly charged barium, Phys. Rev. Lett. 65, 1995 (1990).
  34. P. Beiersdorfer, T. W. Phillips, K. L. Wong, R. E. Marrs, and D. A. Vogel, Measurement of level-specific dielectronic-recombination cross sections of heliumlike Fe xxv, Phys. Rev. A 46, 3812 (1992).
  35. R. Ali, C. P. Bhalla, C. L. Cocke, M. Schulz, and M. Stockli, Dielectronic recombination on and electron-impact excitation of heliumlike argon, Phys. Rev. A 44, 223 (1991).
  36. P. Beiersdorfer, D. A. Vogel, K. J. Reed, V. Decaux, J. H. Scofield, K. Widmann, G. Hölzer, E. Förster, O. Wehrhan, D. W. Savin, and L. Schweikhard, Measurement and interpretation of the polarization of the X-ray line emission of heliumlike Fe XXV excited by an electron beam, Phys. Rev. A 53, 3974 (1996).
  37. A. S. Shlyaptseva, R. C. Mancini, P. Neill, P. Beiersdorfer, J. R. Crespo López-Urrutia, and K. Widmann, Polarization-dependent spectra of X-ray dielectronic satellite lines of Be-like Fe, Phys. Rev. A 57, 888 (1998).
  38. M. Bitter, M. F. Gu, L. A. Vainshtein, P. Beiersdorfer, G. Bertschinger, O. Marchuk, R. Bell, B. LeBlanc, K. W. Hill, D. Johnson, and L. Roquemore, New benchmarks from tokamak experiments for theoretical calculations of the dielectronic satellite spectra of heliumlike ions, Phys. Rev. Lett. 91, 265001 (2003).
  39. G. V. Brown, P. Beiersdorfer, H. Chen, J. H. Scofield, K. R. Boyce, R. L. Kelley, C. A. Kilbourne, F. S. Porter, M. F. Gu, S. M. Kahn, and A. E. Szymkowiak, Energy-dependent excitation cross section measurements of the diagnostic lines of Fe XVII, Phys. Rev. Lett. 96, 253201 (2006).
  40. H. Watanabe, H. Tobiyama, A. P. Kavanagh, Y. M. Li, N. Nakamura, H. A. Sakaue, F. J. Currell, and S. Ohtani, Dielectronic recombination of He-like to C-like iodine ions, Phys. Rev. A 75, 012702 (2007).
  41. C. Beilmann, O. Postavaru, L. H. Arntzen, R. Ginzel, C. H. Keitel, V. Mäckel, P. H. Mokler, M. C. Simon, H. Tawara, I. I. Tupitsyn, J. Ullrich, J. R. Crespo López-Urrutia, and Z. Harman, Intershell trielectronic recombination with K -shell excitation in Kr30+, Phys. Rev. A 80, 050702(R) (2009).
  42. A. P. Kavanagh, H. Watanabe, Y. M. Li, B. E. O'Rourke, H. Tobiyama, N. Nakamura, S. McMahon, C. Yamada, S. Ohtani, and F. J. Currell, Dielectronic recombination in He-like, Li-like, and Be-like highly charged ions in the KLL and KLM manifolds, Phys. Rev. A 81, 022712 (2010).
  43. K. Yao, Z. Geng, J. Xiao, Y. Yang, C. Chen, Y. Fu, D. Lu, R. Hutton, and Y. Zou, KLL dielectronic recombination resonant strengths of He-like up to O-like xenon ions, Phys. Rev. A 81, 022714 (2010).
  44. C. Brandau and C. Kozhuharov, Storage-ring studies of dielectronic recombination as a tool for precision spectroscopy, in Atomic Processes in Basic and Applied Physics (Springer-Verlag, Berlin, 2012), pp. 283–306.
  45. C. Beilmann, P. H. Mokler, S. Bernitt, C. H. Keitel, J. Ullrich, J. R. Crespo López-Urrutia, and Z. Harman, Prominent higher-order contributions to electronic recombination, Phys. Rev. Lett. 107, 143201 (2011).
  46. C. Beilmann, Z. Harman, P. H. Mokler, S. Bernitt, C. H. Keitel, J. Ullrich, and J. R. Crespo López-Urrutia, Major role of multielectronic K - L intershell resonant recombination processes in Li- to O-like ions of Ar, Fe, and Kr, Phys. Rev. A 88, 062706 (2013).
  47. C. Shah, H. Jörg, S. Bernitt, S. Dobrodey, R. Steinbrügge, C. Beilmann, P. Amaro, Z. Hu, S. Weber, S. Fritzsche, A. Surzhykov, J. R. Crespo López-Urrutia, and S. Tashenov, Polarization measurement of dielectronic recombination transitions in highly charged krypton ions, Phys. Rev. A 92, 042702 (2015).
  48. C. Shah, P. Amaro, R. Steinbrügge, C. Beilmann, S. Bernitt, S. Fritzsche, A. Surzhykov, J. R. Crespo López-Urrutia, and S. Tashenov, Strong higher-order resonant contributions to X-ray line polarization in hot plasmas, Phys. Rev. E 93, 061201(R) (2016).
  49. C. Shah, N. Hell, A. Hubbard, M. F. Gu, M. J. MacDonald, M. E. Eckart, R. L. Kelley, C. A. Kilbourne, M. A. Leutenegger, F. S. Porter, and G. V. Brown, High-resolution laboratory measurements of K-shell X-ray line polarization and excitation cross sections in helium-like S XV Ions, Astrophys. J. 914, 34 (2021).
  50. P. Amaro, C. Shah, R. Steinbrügge, C. Beilmann, S. Bernitt, J. R. Crespo López-Urrutia, and S. Tashenov, State-selective influence of the Breit interaction on the angular distribution of emitted photons following dielectronic recombination, Phys. Rev. A 95, 022712 (2017).
  51. I. Orban, S. Mahmood, T. Fritjof, E. Lindroth, C. Z. Dong, J. l. Rui, L. Y. Xie, and R. Schuch, Excitation and recombination studies with silicon and sulphur ions at an EBIT, J. Phys. B 57, 095201 (2024).
  52. C. Shah, P. Amaro, F. Grilo, M. F. Gu, L. Gu, J. P. Santos, F. S. Porter, T. Pfeifer, M. A. Leutenegger, and J. R. Crespo López-Urrutia, Comprehensive laboratory benchmark of K-shell dielectronic satellites of Fe xxv–xxi ions, Astrophys. J. 987, 36 (2025).
  53. V. Azarov, A. Kramida, and Y. Ralchenko, A critical compilation of experimental data on the 1s2l2l′ core-excited states of Li-like ions from carbon to uranium, At. Data Nucl. Data Tables 149, 101548 (2023).
  54. J. E. Rice, M. L. Reinke, J. M. A. Ashbourn, C. Gao, M. M. Victora, M. A. Chilenski, L. Delgado-Aparicio, N. T. Howard, A. E. Hubbard, J. W. Hughes, and J. H. Irby, X-ray observations of Ca19+, Ca18+ and satellites from Alcator C-Mod tokamak plasmas, J. Phys. B 47, 075701 (2014).
  55. J. E. Rice, M. L. Reinke, J. M. A. Ashbourn, C. Gao, M. Bitter, L. Delgado-Aparicio, K. Hill, N. T. Howard, J. W. Hughes, and U. I. Safronova, X-ray observations of medium Z H- and He-like ions with satellites from C-Mod tokamak plasmas, J. Phys. B 48, 144013 (2015).
  56. J. Suleiman, H. G. Berry, R. W. Dunford, R. D. Deslattes, and P. Indelicato, Observations of doubly excited states in lithiumlike calcium, Phys. Rev. A 49, 156 (1994).
  57. https://open.adas.ac.uk/.
  58. S. W. Epp, J. R. Crespo López-Urrutia, G. Brenner, V. Mäckel, P. H. Mokler, R. Treusch, M. Kuhlmann, M. V. Yurkov, J. Feldhaus, J. R. Schneider, M. Wellhöfer, M. Martins, W. Wurth, and J. Ullrich, Soft X-ray laser spectroscopy on trapped highly charged ions at FLASH, Phys. Rev. Lett. 98, 183001 (2007).
  59. S. W. Epp, J. R. Crespo López-Urrutia, M. C. Simon, T. Baumann, G. Brenner, R. Ginzel, N. Guerassimova, V. Mäckel, P. H. Mokler, B. L. Schmitt, H. Tawara, and J. Ullrich, X-ray laser spectroscopy of highly charged ions at FLASH, J. Phys. B 43, 194008 (2010).
  60. F. Grilo, C. Shah, J. Marques, J. P. Santos, J. R. Crespo López-Urrutia, and P. Amaro, Measurement of differential collisional excitation cross sections for the Kα emission of He-like oxygen, Phys. Rev. A 110, 042827 (2024).
  61. F. Grilo, C. Shah, S. Kühn, R. Steinbrügge, K. Fujii, J. Marques, M. F. Gu, J. P. Santos, J. R. Crespo López-Urrutia, and P. Amaro, Comprehensive laboratory measurements resolving the LMM dielectronic recombination satellite lines in Ne-like Fe XVII ions, Astrophys. J. 913, 140 (2021).
  62. J. Clementson, P. Beiersdorfer, G. V. Brown, and M. F. Gu, Spectroscopy of M-shell X-ray transitions in Zn-like through Co-like W, Phys. Scr. 81, 015301 (2010).
  63. C. Shah, S. Dobrodey, S. Bernitt, R. Steinbrügge, J. R. Crespo López-Urrutia, L. Gu, and J. Kaastra, Laboratory measurements compellingly support a charge-exchange mechanism for the “dark matter” ∼3.5 keV X-ray line, Astrophys. J. 833, 52 (2016).
  64. C. Shah, J. R. Crespo López-Urrutia, M. F. Gu, T. Pfeifer, J. Marques, F. Grilo, J. P. Santos, and P. Amaro, Revisiting the Fe XVII line emission problem: Laboratory measurements of the 3s–2p and 3d–2p line-formation channels, Astrophys. J. 881, 100 (2019).
  65. M. F. Gu, The flexible atomic code, Can. J. Phys. 86, 675 (2008).
  66. M. F. Gu, D. W. Savin, and P. Beiersdorfer, Effects of electron spiralling on the anisotropy and polarization of photon emission from an electron beam ion trap, J. Phys. B: At. Mol. Opt. Phys. 32, 5371 (1999).
  67. M. F. Gu, S. M. Kahn, D. W. Savin, P. Beiersdorfer, G. V. Brown, D. A. Liedahl, K. J. Reed, C. P. Bhalla, and S. R. Grabbe, Laboratory measurements of Fe XXIV Line emission: 3→2 transitions near excitation threshold, Astrophys. J. 518, 1002 (1999).
  68. C. Shah, P. Amaro, R. Steinbrügge, S. Bernitt, J. R. Crespo López-Urrutia, and S. Tashenov, Polarization of K-shell dielectronic recombination satellite lines of Fe xix–xxv and its application for diagnostics of anisotropies of hot plasmas, Astrophys. J. Suppl. Ser. 234, 27 (2018).
  69. G. Herrmann, Optical theory of thermal velocity effects in cylindrical electron beams, J. Appl. Phys. 29, 127 (1958).
  70. A. H. Gabriel, Dielectronic satellite spectra for highly-charged helium-like Ion lines, Mon. Not. R. Astron. Soc. 160, 99 (1972).
  71. I. Antcheva, M. Ballintijn, B. Bellenot, M. Biskup, R. Brun, N. Buncic, P. Canal, D. Casadei, O. Couet, V. Fine, L. Franco, G. Ganis, A. Gheata, D. G. Maline, M. Goto, J. Iwaszkiewicz, A. Kreshuk, D. M. Segura, R. Maunder, L. Moneta, et al., root — A C++ framework for petabyte data storage, statistical analysis and visualization, Comput. Phys. Commun. 180, 2499 (2009).
  72. B. M. Penetrante, J. N. Bardsley, D. DeWitt, M. Clark, and D. Schneider, Evolution of ion-charge-state distributions in an electron-beam ion trap, Phys. Rev. A 43, 4861 (1991).
  73. S. Lloyd, Least squares quantization in PCM, IEEE Trans. Inf. Theory 28, 129 (1982).
  74. M. Cornille, J. Dubau, and U. I. Safronova, Energies and autoionization rates for Be-like systems. comparison of two methods: AUTOLSJ and MZ, Phys. Scr. 48, 546 (1993).
  75. L. Vainshtein and U. Safronova, Wavelengths and transition probabilities of satellites to resonance lines of H- and He-like ions, At. Data Nucl. Data Tables 21, 49 (1978).
  76. W. Eissner, M. Jones, and H. Nussbaumer, Techniques for the calculation of atomic structures and radiative data including relativistic corrections, Comput. Phys. Commun. 8, 270 (1974).
  77. M. F. Gu, Dielectronic recombination rate coefficients for H-like through Ne-like isosequences of Mg, Si, S, Ar, Ca, Fe, and Ni, Astrophys. J. 590, 1131 (2003).
  78. https://heasarc.gsfc.nasa.gov/docs/xrism/.
  79. A. N. Artemyev, V. M. Shabaev, V. A. Yerokhin, G. Plunien, and G. Soff, QED calculation of the n=1 and n=2 energy levels in He-like ions, Phys. Rev. A 71, 062104 (2005).
  80. F. Pajot, D. Barret, T. Lam-Trong, J.-W. Den Herder, L. Piro, M. Cappi, J. Huovelin, R. Kelley, J. Mas-Hesse, K. Mitsuda, et al., The athena X-ray integral field unit (X-IFU), J. Low Temp. Phys. 193, 901 (2018).
  81. W. R. Johnson, I. M. Savukov, U. I. Safronova, and A. Dalgarno, E1 transitions between states with n=1−6 in helium-like carbon, nitrogen, oxygen, neon, silicon, and argon, Astrophys. J. Suppl. Ser. 141, 543 (2002).
  82. J.-Y. Liao, S.-N. Zhang, and Y. Yao, Wavelength measurements of K transitions of oxygen, neon, and magnesium with X-ray absorption lines, Astrophys. J. 774, 116 (2013).
  83. Y. Yao, N. S. Schulz, M. F. Gu, M. A. Nowak, and C. R. Canizares, High-resolution X-ray spectroscopy of the multiphase interstellar medium toward Cyg X-2, Astrophys. J. 696, 1418 (2009).
  84. J. Machado, C. I. Szabo, J. P. Santos, P. Amaro, M. Guerra, A. Gumberidze, G. Bian, J. M. Isac, and P. Indelicato, High-precision measurements of n=2→n=1 transition energies and level widths in He- and Be-like argon ions, Phys. Rev. A 97, 032517 (2018).
  85. K. Kubiçek, P. H. Mokler, V. Mäckel, J. Ullrich, and J. R. Crespo López-Urrutia, Transition energy measurements in hydrogenlike and heliumlike ions strongly supporting bound-state QED calculations, Phys. Rev. A 90, 032508 (2014).
  86. R. D. Deslattes, H. F. Beyer, and F. Folkmann, Precision X-ray wavelength measurements in helium-like argon recoil ions, J. Phys. B 17, L689 (1984).
  87. J. P. Briand, J. P. Mossé, P. Indelicato, P. Chevallier, D. Girard-Vernhet, A. Chetioui, M. T. Ramos, and J. P. Desclaux, Spectroscopy of hydrogenlike and heliumlike argon, Phys. Rev. A 28, 1413 (1983).
  88. H. D. Dohmann, D. Liesen, and H. Pfeng, High resolution spectroscopy of prompt and metastable decaying levels in highly ionized argon, especially of the metastable 3P2-state of Ar16+ and the 4P5/2-state of Ar15+, Z. Phys. A 285, 171 (1978).
  89. P. Amaro, S. Schlesser, M. Guerra, E.-O. Le Bigot, J.-M. Isac, P. Travers, J. P. Santos, C. I. Szabo, A. Gumberidze, and P. Indelicato, Absolute measurement of the relativistic magnetic dipole transition energy in heliumlike Argon, Phys. Rev. Lett. 109, 043005 (2012).
  90. E. V. Aglitsky, P. S. Antsiferov, S. L. Mandelstam, A. M. Panin, U. I. Safronova, S. A. Ulitin, and L. A. Vainshtein, Comparison of calculated and measured wavelengths of resonance transitions in He-like ions for Z=16−39, Phys. Scr. 38, 136 (1988).
  91. E. Tiesinga, P. J. Mohr, D. B. Newell, and B. N. Taylor, CODATA recommended values of the fundamental physical constants: 2018, J. Phys. Chem. Ref. Data 50, 033105 (2021).

Outline

Information

Phys. Rev. A 113, 032819– Published 27 March, 2026
  • Received 13 August 2025
  • Revised 27 January 2026
  • Accepted 18 February 2026
Crossmark - Check for updates button
Creative Commons Logo

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Open access publication funded by Max Planck Society.

Published by the American Physical Society

Sign In to Your Journals Account

Filter

Filter

Article Lookup

Enter a citation