Investigation on the DC Stark shifts of strontium autoionization states for isotope-selective resonance ionization. (May 2021)

• Record Type: Journal Article
• Authors: Iwata, Yoshihiro; Miyabe, Masabumi; Hasegawa, Shuichi
• Is Part Of: Journal of quantitative spectroscopy & radiative transfer. Volume 265(2021)
• Publication Date: 2021-05
• Subjects: Strontium -- Isotope-selective resonance ionization -- DC Stark shift -- Polarizability -- Autoionization states -- Rydberg level; Spectrum analysis -- Periodicals; Radiation -- Periodicals; Analyse spectrale -- Périodiques; Rayonnement -- Périodiques; Radiation; Spectrum analysis; Periodicals; 543.0858
• DOI: 10.1016/j.jqsrt.2021.107549
• Languages: English
• ISSNs: 0022-4073

Abstract

Highlights: We measured for the first time the DC Stark shifts of ten Rydberg levels (n e f f 36–39, 50–55) of 88 Sr converging to the 4d 2 D 3 / 2 limit. The polarizability α of each level was evaluated to be | α | 10 − 30 − 10 − 28 [ C 2 m 2 J − 1 ] depending on the effective principal quantum number neff . The residual electric field in the ionization region should be of the order of 0.1 V/cm or less for trace analysis of radioisotope 90 Sr using three-step resonance excitation. For some Rydberg levels, another nearby level was also observed with the applied electric field, implying that the DC Stark shift allows observation of forbidden transitions. Abstract: Three-step resonance excitation to autoionization states is a promising isotope-selective ionization technique for atomic strontium (Sr). We measured for the first time the DC Stark shifts of ten Rydberg levels ( n eff ∼ 36 − 39, 50 − 55 ) of 88 Sr converging to the 4d 2 D 3 / 2 limit using the 5s 2 1 S 0 → 5s5p 1 P 1 ∘ → 5p 2 1 D 2 → (4d 2 D 3 / 2 Rydberg series) transition pathway. The polarizability α of each level was evaluated to be | α | ∼ 10 − 30 − 10 − 28 [C 2 · m 2 · J − 1 ] depending on the effective principal quantum number n eff, which indicates that the external electric field E in the ionization region should be of the order of 0.1 V/cm or less to suppress its effect on the observed spectra. Our experimental data on the DC Stark shift and polarizability of the Rydberg levels are useful for future isotope-selective detection of the radioisotope 90 Sr using three-step resonance excitation.