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The FERRUM project: metastable lifetimes in Cr II
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
Stockholm University, Faculty of Science, Department of Physics.
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2012 (English)In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 420, no 2, 1636-1639 p.Article in journal (Refereed) Published
Abstract [en]

Parity forbidden radiative transitions from metastable levels are observed in spectra of low-density astrophysical plasmas. These lines are used as probes of the physical conditions, made possible due to the long lifetime of their upper level. In a joint effort, the FERRUM project aims to obtain new and accurate atomic data for the iron-group elements, and part of this project concerns forbidden lines. The radiative lifetimes of the metastable energy levels 3 d4(a 3 D)4 s c4 D 5/2 and 3 d4(a 3 D)4 s c4 D 7/2 of singly ionized chromium have been measured. The experiment has been performed at the ion storage ring CRYRING. We employed a laser-probing technique developed for measuring long lifetimes. In this article, we present the lifetimes of these levels to be t5/2= 1.28(16) s and t7/2= 1.37(7) s, respectively. A comparison with previous theoretical work shows good agreement and the result is discussed in a theoretical context.

Place, publisher, year, edition, pages
2012. Vol. 420, no 2, 1636-1639 p.
Keyword [en]
atomic data, methods: laboratory, techniques: spectroscopic, astronomical data bases: miscellaneous
National Category
Atom and Molecular Physics and Optics
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-67023DOI: 10.1111/j.1365-2966.2011.20152.xISI: 000299417600056OAI: oai:DiVA.org:su-67023DiVA: diva2:469139
Funder
Swedish Research Council, 2006-3085Swedish Research Council, 2008-3736
Available from: 2011-12-22 Created: 2011-12-22 Last updated: 2017-12-08Bibliographically 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. 88 p.
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: 2015-02-26Bibliographically approved

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