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Journal of the Optical Society of America B

Resonance ionization spectroscopy of high-lying 4sns and 4snd Rydberg levels of odd calcium isotopes

Yoshihiro Iwata, Masabumi Miyabe, Katsuaki Akaoka, Ikuo Wakaida, Shuichi Hasegawa

Published Nov 22, 2023• 5 citations
Publisher

Abstract

Calcium Rydberg levels are of significant interest for efficient and isotope-selective resonance ionization of trace radionuclides such as calcium-41 ( 41 Ca). In this study, we report novel, to our knowledge, measurement data on the energy level shifts of 43 Ca for 4sns 1 S 0 and 4s(n−1)d 1 D 2 (n=40, 45, 50, 55, 60) Rydberg levels due to hyperfine-induced singlet–triplet mixing specific to isotopes with an odd mass number. Both 3 S 1 and 3 D J triplet signals corresponding to forbidden transitions were enhanced for 43 Ca at the high principal quantum numbers n=55 and 60, indicating a mixing of singlet components to some extent.

DOI
10.1364/josab.507539

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Calcium Rydberg levels are of significant interest for efficient and isotope-selective resonance ionization of trace radionuclides such as calcium-41 ( 41 Ca). In this study, we report novel, to our knowledge, measurement data on the energy level shifts of 43 Ca for 4sns 1 S 0 and 4s(n−1)d 1 D 2 (n=40, 45, 50, 55, 60) Rydberg levels due to hyperfine-induced singlet–triplet mixing specific to isotopes with an odd mass number. Both 3 S 1 and 3 D J triplet signals corresponding to forbidden transitions were enhanced for 43 Ca at the high principal quantum numbers n=55 and 60, indicating a mixing of singlet components to some extent.
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Singlet-triplet mixing of 4snd1D24snd ^{1}D_{2}4snd1D2​ and 3D2^{3}D_{2}3D2​ states of Ca was determined between principal quantum numbers 7< n< 427<~n<~427< n< 42 with the use of Doppler-free two-photon spectroscopy. The hyperfine structure of the 4snd1D24snd ^{1}D_{2}4snd1D2​ states was used to probe admixtures of triplet character into the singlet wave functions. It turned out that, in the region of series crossings, an enlarged singlet-triplet mixing was observed.
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