Hannover 2020 – scientific programme
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A: Fachverband Atomphysik
A 20: Precision spectroscopy of atoms and ions III
A 20.3: Talk
Wednesday, March 11, 2020, 14:45–15:00, f303
Electronic bridge excitation in highly charged 229Th ions — •Pavlo Bilous, Hendrik Bekker, José R. Crespo López-Urrutia, and Adriana Pálffy — Max Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany
Of all nuclei, the 229Th isotope possesses an extremely low-lying nuclear isomer at approx. 8 eV. This nuclear transition has the potential to provide a first nuclear frequency standard at an unprecedented accuracy, a laser operating between nuclear sublevels, and the coherent control of a nuclear excitation with a VUV laser. The practical implementation of these applications requires however a way to directly drive the isomer with a narrow band VUV laser, and in turn the precise knowledge of its energy which according to the most recent experimental results is Em=8.28 ± 0.17 eV [1].
In this theoretical work we investigate a method to populate the Th isomer in highly charged ions produced in an electron beam ion trap using a tunable UV laser. The employed excitation mechanism, the so-called electronic bridge, occurs via the electronic shell, which is first promoted by a laser photon to a virtual state with subsequent energy transfer to the nucleus. With the absorbed laser photon energy directly related to the isomer energy Em, this mechanism promises the determination of Em with an accuracy of 10−4 eV which is limited by the Doppler broadening of the ions in the trap. Our theoretical results show that this scheme is feasible under presently available experimental parameters.
[1] B. Seiferle et al., Nature 573, 243–246 (2019).