Binding Energies and Lifetimes in Negative Ions
Abstract
Negative ions hold significant interest because of their importance in understanding electron correlation. Further, they capture substantial focus for their role in, for example: stellar environments, medical applications, antimatter research, and accelerator mass spectrometry (AMS).
This thesis covers experimental studies of both the structure and
dynamics of negative ions at the ion beam facilities DESIREE (Double
ElectroStatic Ion Ring ExpEriment), CERN-ISOLDE (Isotope Separator
OnLine DEvice) and GUNILLA (Gothenburg University Negative Ion
and Laser LAboratory).
At DESIREE, the electron affinites (EA) for the three stable isotopes of silicon have been measured with high precision, using lasermanipulation of quantum-state populations followed by laser photodetachment threshold (LPT) spectroscopy. The corresponding isotope shifts
in the EA have been calculated. Additionally, the hyperfine splitting of
the ground state in 29Si− was measured.
The EA for two radioactive isotopes, 128I and 211At, have been
determined using LPT spectroscopy with the GANDALPH (Gothenburg
ANion Detector for Affinity measurements by Laser PHotodetachment)
detector at ISOLDE. These are the first ever EA measurements of
radioactive isotopes. This opens up a whole new field of experiments
where the EA of even heavier ions can be measured, and giving the
possibility of measuring isotope shifts in radioactive isotopes.
At the ion beam facility GUNILLA at the University of Gothenburg,
the EA for rubidium has been measured using a state selective detection
of the residual atom in the LPT processes. If this selective measurement
technique is combined with the possibility of studying radioactive beams
at ISOLDE, it can be applied to studies of rare anions, like francium.
In terms of dynamical properties, the radiative lifetimes of excited
states in several atomic and molecular anions have been measured at
DESIREE and some previously unobserved energy states have been
detected. The methods used for detailed studies of the structure of
negative ions used in this work lay the foundation for the ultimate goal
to map out the lifetimes of all the excited states in negative ions.
The research presented in here shows that it is only by combining
structural and dynamical experimental results that it is possible to
obtain a complete picture of negative ions. The results shown so far
have been used to benchmark theoretical methods, but there are still
quite a few discrepancies. By applying the methods used in this work
to the full range of elements in the periodic table, and comparing them
with theoretical results, it will be possible to enhance our understanding
of electron correlation. Of particular interest will be to study the very
heavy systems, where relativistic effects play a decisive role.
Parts of work
1. J. Karls, H. Cederquist, N. D. Gibson, J. Grumer, M. Ji, I. Kardasch, D. Leimbach, P. Martini, J. E. Navarro Navarrete, R. Poulose, S. Rosén, H. T. Schmidt, A. Simonsson, H. Zettergren and D. Hanstorp, "Precision measurements on Si−", In manuscript (2024). 2. S. Rothe, J. Sundberg, J. Welander, K. Chrysalidis, T. Day Goodacre, V. Fedosseev, S. Fiotakis, O. Forstner, R. Heinke, K. Johnston, T. Kron, U. Köster, Y. Liu, B. Marsh, A. Ringvall-Moberg, R. E. Rossel, C. Seiffert, D. Studer, K. Wendt and D. Hanstorp, "Laser photodetachment of radioactive 128I-", J. Phys. G Nucl. Part. Phys., 44, 104003 (2017), https://doi.org/10.1088/1361-6471/aa80aa 3. D. Leimbach, S. Rothe, L. Bengtsson, A. Ringvall-Moberg, J. Sundberg, K. Wendt and D. Hanstorp, "Upgrades of the GANDALPH photodetachment detector towards the determination of the electron affinity of astatine", Nucl. Instrum. Methods Phys. Res. B: Beam Interact. Mater. At., 463, 277–279 (2020), https://doi.org/10.1016/j.nimb.2019.05.015 4. D. Leimbach, J. Karls, Y. Guo, R. Ahmed, J. Ballof, L. Bengtsson, F. Boix Pamies, A. Borschevsky, K. Chrysalidis, E. Eliav, D. Fedorov, V. Fedosseev, O. Forstner, N. Galland, R. F. Garcia Ruiz, C. Granados, R. Heinke, K. Johnston, A. Koszorus, U. Köster, M. K. Kristiansson, Y. Liu, B. Marsh, P. Molkanov, L. F. Pasteka, J. P. Ramos, E. Renault, M. Reponen, A. Ringvall-Moberg, R. E. Rossel, D. Studer, A. Vernon, J. Warbinek, J. Welander, K. Wendt, S. Wilkins, D. Hanstorp and S. Rothe, "The electron affinity of astatine", Nat. Commun. 11, 3824 (2020), https://doi.org/10.1038/s41467-020-17599-2 5. A. Ringvall-Moberg, M. Nichols, J. E. Navarro Navarrete, U. B̄erzinš, V. D’mello, J. Karls, D. Lu, Y. Peña Rodríguez, R. Poulose, A. Morales Rodr´ıguez, K. Ravi, M. Ramachandran, V. Zhaunerchyk, D. Hanstorp, and D. Leimbach, "The electron affinity of rubidium: A state selective measurement", Submitted to J. Phys. B: At. Mol. Opt. Phys. (2024). 6. M. K. Kristiansson, S. Schiffmann, J. Grumer, J. Karls, N. de Ruette, G. Eklund, V. Ideböhn, N. D. Gibson, T. Brage, H. Zettergren, D. Hanstorp and H. T. Schmidt, "Experimental and theoretical studies of the excited states of Ir-", Phys. Rev. A 103, 062806 (2021), https://doi.org/10.1103/PhysRevA.103.062806 7. J. Karls, J. Grumer, S. Schiffmann, N. D. Gibson, M. Ji, M. K. Kristiansson, D. Leimbach, J. E. Navarro Navarrete, Y. Peña Rodríguez, R. Ponce, A Ringvall-Moberg, H. T. Schmidt, S. E. Spielman, C. W. Walter, T. Brage and D. Hanstorp, "Lifetimes of excited states in Rh-", In manuscript (2024). 8. M. K. Kristiansson, J. Karls, N. D. Gibson, D. Hanstorp, H. T. Schmidt and C. W. Walter, "Measurement of the lifetime of a metastable excited state in Bi-", Phys. Rev. A 105, L010801, (2022), https://doi.org/10.1103/PhysRevA.105.L010801 9. J. Karls, M. Björkhage, M. Blom, N. D. Gibson, O. Hemdal Lundgren, M. Ji, M. K. Kristiansson, D. Leimbach, J. E. Navarro Navarrete, P. Reinhed, A. Ringvall-Moberg, S. Rosén, H. T. Schmidt, A.
Simonsson and D. Hanstorp, "Lifetimes of excited states in P-, As- and Sb-", In manuscript (2024). 10. C. W. Walter, F. E. Vassallo, J. Karls, J. E. Navarro Navarrete, D. Leimbach, O. H. Lundgren, M. K. Kristiansson, M Björkhage, R. D. Thomas, H. Zettergren, H. T. Schmidt, D. Hanstorp and N. D. Gibson, "Lifetimes of excited states of the lanthanum negative ion", In manuscript (2024). 11. H. Gnaser, M. Martschini, D. Leimbach, J. Karls, D. Hanstorp, S. Indrajith, M. Ji, P. Martini, A. Simonsson, H. Zettergren, H. T. Schmidt and R. Golser, "Spontaneous and photo-induced decay processes of WF5- and HfF5- molecular anions in a cryogenic storage ring", J. Chem. Phys. 157, 044304, (2022), https://doi.org/10.1063/5.0097896
Degree
Doctor of Philosophy
University
University of Gothenburg
Institution
Department of Physics ; Institutionen för fysik
Disputation
Torsdagen den 25 april, kl. 10.00, PJ-salen, Institutionen för fysik, Kemigården 1.
Date of defence
2024-04-25
julia.karls@physics.gu.se
Date
2024-03-15Author
Karls, Julia
Keywords
Atomic Physics
Electron Correlation
Electron Affinity
Isotope Shifts
Photodetachment
Negative Ions
Anions
Radioisotopes
Laser Photodetachment Spectroscopy
Resonance Ionization
Neutral Particle Detection
Wigner Threshold Law
DESIREE
ISOLDE
CERN
Radiative Lifetimes
Publication type
Doctoral thesis
ISBN
978-91-8069-665-4 (TRYCK)
978-91-8069-666-1 (PDF)
Language
eng