Sprecher
Beschreibung
We theoretically investigate the angular distributions of fluorescence and photoelectrons emission based on density matrix formalism [1] in a pump-probe scheme dedicated for measuring the lifetime of odd singlet excited states of C III [2]. The energy levels, bound-bound and bound-free electric dipole matrix elements belonging to C III have been computed with the Dirac-Fock-Slater model-potential method in combination with the distorted wave approximation for free states [3]. The quasi-bound states embedded in continuum are treated within time-independent perturbation theory [4]. During the pumping stage, triplet states also couple to the singlet ground state through spin-flip transitions affecting the overall yield and angular distribution of fluorescence. Similarly, during the probing stage, the ensemble of atoms excited in closely-lying states participate in the photoionization process, altering the expected C IV ion yield and the partial wave expansion of photoelectrons. The composition of the latter is investigated and highlighted by comparing the electron polarization [5] in the case of photoionization of carbon ions excited within a single state versus photoionization from a similar ensemble excited into multiple closely-lying states.
Acknowledgement: This research was supported by Romanian Ministry of Research, Innovation and Digitalization under Romanian National Nucleu Program LAPLAS VII, Contract No. 30N/2023. Partial financial support from the Institute of Atomic Physics under Project No. F01/2020 is also acknowledged
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[2] J. Rothhardt, M. Bilal, R. Beerwerth, A.V. Volotka, V. Hilbert, T. Stöhlker, S. Fritzsche, J. Limpert, X-ray Spectrometry 49, 165-168, 2020.
[3] M. F. Gu, Flexible Atomic Code, Can. J. Phys 86 (2008), 675-689.
[4] U. Fano, Effects of Configuration Interaction on the Intensities and Phase Shifts, Phys. Rev. A 124(1961), 1866-1878.
[5] C. Iorga and V. Stancalie, Linear polarization of the dielectronic recombination Kα satellite lines in Li-like Au76+, JQSRT 224(2019), 206-216.
