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Abstract
In recent years, various highly charged ions (HCI) with optical transitions have been proposed for metrology and searches of a possible variation of the fine-structure constant α. Optical transitions in HCI are uncommon due to the scaling of energy levels with atomic number Z^2 . At the 4f–5s level crossing, three configurations are nearly degenerate, and thus many optical transitions can exist. The complex many-electron couplings reduce the accuracy of current calculations. Moreover, experimental data to benchmark the predictions is lacking. Spectra in the optical and extreme-ultraviolet (EUV) range of several ion species near the 4f–5s level crossing were measured at the Heidelberg electron beam ion trap. A collisional-radiative model was employed for the interpretation of the EUV data, resulting in the first identification of the long sought-after 5s–5p transitions in Pm-like Re^14+ , Os^15+ , Ir^16+ , and Pt^17+. The characteristic line shapes of optical transitions in Ir17+ were studied, with the aim of identifying transitions with a high sensitivity to α-variation. Previously suggested candidates could be excluded and new candidates were proposed. This data provides a stringent benchmark for state-of-the-art precision atomic theory.
Document type: | Dissertation |
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Supervisor: | Crespo López-Urrutia, PD Dr. José R. |
Date of thesis defense: | 18 May 2016 |
Date Deposited: | 01 Jun 2016 07:42 |
Date: | 2016 |
Faculties / Institutes: | The Faculty of Physics and Astronomy > Institute of Physics |
DDC-classification: | 500 Natural sciences and mathematics 530 Physics |