UNIVERSITY OF BUCHAREST
FACULTY OF PHYSICS

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Conference: Bucharest University Faculty of Physics 2018 Meeting


Section: Theoretical Physics and Applied Mathematics


Title:
Linear polarization of x-ray lines arising from 1s-2p transitions emitted in the recombination process of highly charged ions


Authors:
Cristian IORGA (1,2), Viorica STANCALIE (1)


*
Affiliation:
1) National Institute for Laser Plasma and Radiation Physics, Atomistilor 409, P. O. Box Mg-36, Magurele-Ilfov 077125, Romania

2) University of Bucharest, Faculty of Physics, Atomistilor 405, CP-MG 11, Magurele-Bucharest 077125, Romania



E-mail
criiorga@gmail.com


Keywords:
highly charged ions, x-rays, linear polarization, dielectronic recombination


Abstract:
Line intensity ratios belonging to highly charged ions have been used for decades to accurately determine plasma parameters. One may extract further information from the system, such as atomic level splitting [1], different order multipole contributions to emitted light [2], lifetime interference [3], by measuring the degree of linear polarization for certain transitions. A great candidate for such measurements are the X-rays emitted during the competing radiative and dielectronic recombination processes [4] for He-like ions with incoming electrons of different kinetic energies. While lower energy electrons can directly recombine forming Li-like bound states following the emission of a photon, electrons with higher energies have a greater tendency to form highly unstable doubly-excited resonances that may decay radiatively or through Auger processes. We theoretically study the degree of polarization of x-ray satellite lines emitted from 1s2pnl resonances decaying to 1s2nl states via the density-matrix approach [5] for highly-charged W71+, Au76+ and U89+ ions. The interference effects between high-lying resonances is shown to significantly enhance the linear polarization of emitted lines when the energy separation between levels becomes smaller.


References:

[1] Z. W. Wu, A. Surzhykov, N. M Kabachnik, C. Z. Dong, and S. Fritzsche, Journal of Physics: Conference Series 635, 012020, 2015.

[2] Z. B. Chen, J. L. Zeng, H. W. Hu and C. Z. Dong, J. Phys. B: At. Mol. Opt. Phys. 48, 144005, 2015.

[3] K. Ueda, Y. Shimizu, N. M. Kabachnik, I. P. Sazhina, R. Wehlitz, U. Becker, M. Kitajima and H. Tanaka, J. Phys. B: At. Mol. Opt. Phys. 32(13), L291-L296, 1999.

[4] M. K. Inal and J. Dubau, J. Phys. B: At. Mol. Opt. Phys. 22, 3329-3341, 1989.

[5] K. Bloom, Physics of atoms and molecules: Density-matrix theory and applications, (New York: Plenum) 1981.



Acknowledgement:
Acknowledgement: this work has been financed by the Institute of Atomic Physics through the FAIR-RO project “Atomic interactions in supercritical fields: preliminary investigations for SPARC in-kind contributions (SPARC-RO)”.