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Storing keV negative ions for an hour: The lifetime of the metastable 2P1/2 level in 32S−
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics. Jan Kochanowski University, Poland.
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2015 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 114, no 14, article id 143003Article in journal (Refereed) Published
Abstract [en]

We use a novel electrostatic ion storage ring to measure the radiative lifetime of the upper level in the 3p 5  P 2  o 1/2 →3p 5  P 2  o 3/2   spontaneous radiative decay in S −  32   to be 503±54  sec . This is by orders of magnitude the longest lifetime ever measured in a negatively charged ion. Cryogenic cooling of the storage ring gives a residual-gas pressure of a few times 10 −14   mbar at 13 K and storage of 10 keV sulfur anions for more than an hour. Our experimental results differ by 1.3σ  from the only available theoretical prediction.

Place, publisher, year, edition, pages
2015. Vol. 114, no 14, article id 143003
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-114302DOI: 10.1103/PhysRevLett.114.143003ISI: 000352192200009OAI: oai:DiVA.org:su-114302DiVA, id: diva2:791037
Funder
Swedish Research Council, 821-2013-1642Swedish Research Council, 621-2012-3662Swedish Research Council, 621-2011-4047Swedish Research Council, 621-2013-4084Available from: 2015-02-26 Created: 2015-02-26 Last updated: 2018-11-14Bibliographically approved
In thesis
1. Time-Resolved Spectroscopy and Intensity Measurements of Singly Charged Ions
Open this publication in new window or tab >>Time-Resolved Spectroscopy and Intensity Measurements of Singly Charged Ions
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis is mainly concerned with investigations of spontaneous radiatively decaying states in both negative and positive singly charged ions. When possible, the measured lifetime of the state has been combined with branching fractions in order to derive the absolute transition probability (A-value) between different quantum states. The radiative transition probability between two quantum states is a fundamental atomic property. Knowledge of this property can be used as a diagnostic tool in, for example, abundance and temperature determinations with applications in many fields, e.g. astronomy, plasma physics, atomic physics etc.

The focus of the experiments has been on lifetime measurements of long-lived metastable states. Lifetimes of long-lived metastable states are interesting in both theoretical aspects as well as the challenge it poses to the experimentalist. To perform such experiments, impact from the surrounding environment on the stored ions has to be kept to a minimum for extended periods of time. The metastable lifetimes presented here have been measured with time-resolved laser spectroscopic techniques in two different types of ion storage rings. One of them is a new type of unique cryogenically cooled storage ring made of purely electrostatic ion optical elements. As is demonstrated in this thesis, this device opens up a completely new time domain where lifetime measurements now can be performed. In addition, this thesis includes a discussion and preliminary studies of weak interactions otherwise limited by magnetic fields and/or thermal radiation from the environment. When available, the results have been compared to previous measurements and theoretical calculations which enables an evaluation of different methods and theoretical models.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University, 2015. p. 88
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-113503 (URN)978-91-7649-100-3 (ISBN)
Public defence
2015-03-20, sal FB42, AlbaNova universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 6: Accepted.

Available from: 2015-02-26 Created: 2015-02-03 Last updated: 2019-10-16Bibliographically approved
2. Radiative lifetimes of bound excited states in anions: Measurements on long-lived metastable states in atomic anions
Open this publication in new window or tab >>Radiative lifetimes of bound excited states in anions: Measurements on long-lived metastable states in atomic anions
2018 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis presents and discusses the results of measurements of the intrinsic lifetimes of bound excited anionic states. The results are valuable for evaluation of different theoretical models and computation methods and are compared to calculations when available. The measurements were carried out at the DESIREE facility located in the AlbaNova University Center in Stockholm. The storage ring used is cryogenically cooled and has a very low residual gas density. Both of these features are needed for the storage of some bound excited anionic states, as blackbody radiation would otherwise photodetach the state. Residual gas density is the main limiting factor for storage lifetime in the presented measurements. The majority of the work has been in the development and refinement of the laser probing technique utilized for the measurements, which had to be adapted for each anion to account for the different time-domains and wavelengths required.

The published results was a radiative lifetime of 503±54 seconds for the 3p5 2P1/2 state in sulfur, 15.1±0.4 seconds for the 4s2 2D3/2 state in nickel and 2.54±0.10 seconds for the 5d10 6s 2S1/2 state in platinum. The radiative lifetime of the 5d9 6s2 2D3/2 state in platinum could only be estimated to a range of 50 ms to 200 ms.

Place, publisher, year, edition, pages
Stockholm University, 2018. p. 64
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-162168 (URN)
Available from: 2019-06-11 Created: 2018-11-14 Last updated: 2019-06-11Bibliographically approved

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Bäckström, ErikHole, Odd MagnarKaminska, MagdalenaNascimento, Rodrigo F.Blom, MikaelBjörkhage, MikaelKällberg, AndersLöfgren, PatrikReinhed, PeterRosén, StefanSimonsson, AnsgarThomas, Richard D.Mannervik, SvenSchmidt, Henning T.Cederquist, Henrik
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