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A: Fachverband Atomphysik

A 17: Collisions, scattering and correlation phenomena

A 17.2: Talk

Wednesday, March 16, 2022, 14:30–14:45, A-H1

Spectroscopy of metastable states of Si⁻ — •Suvam Singh, Chunhai Lyu, Christoph Keitel, and Zoltán Harman — Max Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany

In this work [1], we have calculated photodetachment cross sections (PDCS), electron affinities, fine-structure splittings, transition energies, and radiative lifetimes of all the metastable states of the Si⁻ ion. All atomic state functions for the description of Si and Si⁻ ion have been generated by the Multiconfiguration Dirac-Hartree-Fock method. Here, we have used the grasp2K and RATIP codes to carry out dedicated calculations of the PDCS of all anionic states of Si⁻ at two specific photon energies, namely, at 0.89 eV and 1.95 eV. The choice of the photon energies is motivated by very recent low-background measurements with the Cryogenic Storage Ring (CSR) of the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg, Germany. The PDCS are used in analyzing experimental data obtained by the CSR at MPIK. To independently predict the electron affinities, fine-structure splittings, transition energies, and radiative lifetimes, we have used the MCDHF method in combination with the relativistic configuration interaction approach. These calculations were performed using the GRASP2018 code, performing a systematic expansion of the atomic states in terms of a large number of configuration state functions to obtain accurate predictions. Detailed results will be presented during the conference.

Reference: [1] D. Müll et al., Phys. Rev. A, 104 (2021) 032811.