Laser spectroscopy of the $$^2{\mathrm{S}}_{1/2}{-}^2{\mathrm{P}}_{{1}/2}$$, $$^2{\mathrm{P}}_{3/2}$$ transitions in stored and cooled relativistic C3+ ions

Abstract

The $$^2{\mathrm{S}}_{1/2}{-}^2{\mathrm{P}}_{{1}/2}$$ 2 S 1 / 2 - 2 P 1 / 2 and $$^2{\mathrm{S}}_{1/2}{-}^2{\mathrm{P}}_{{3}/2}$$ 2 S 1 / 2 - 2 P 3 / 2 transitions in Li-like carbon ions stored and cooled at a velocity of $$\beta \approx 0.47$$ β ≈ 0.47 in the experimental storage ring (ESR) at the GSI Helmholtz Centre in Darmstadt have been investigated in a laser spectroscopy experiment. Resonance wavelengths were obtained using a new continuous-wave UV laser system and a novel extreme UV (XUV) detection system to detect forward emitted fluorescence photons. The results obtained for the two transitions are compared to existing experimental and theoretical data. A discrepancy found in an earlier laser spectroscopy measurement at the ESR with results from plasma spectroscopy and interferometry has been resolved and agreement between experiment and theory is confirmed.

Transition frequencies between 2S and 2P states of lithium-like ions

“…For C 3+ , our theoretical result 7.994 956 (14) eV for the 2S 1/2 -2P 1/2 transition agrees with the experimental result 7.994 954 (11) eV measured by Griesmann and Kling with interferometry [24] very well, and also agrees with the recent experimental result 7.994 962(62) eV measured by Winzen et al with laser spectroscopy. [25] For the transition 2S 1/2 -2P 3/2 , our result 8.008 238 (14) eV agrees with Griesmann and Kling's experimental result 8.008 262 1(50) eV [24] within 2σ , and agrees with the lower accurate experimental results 8.008 224(62) in Ref. [25].…”

“…[25] For the transition 2S 1/2 -2P 3/2 , our result 8.008 238 (14) eV agrees with Griesmann and Kling's experimental result 8.008 262 1(50) eV [24] within 2σ , and agrees with the lower accurate experimental results 8.008 224(62) in Ref. [25].…”

“…More accurate experimental results have also been given in Refs. [23][24][25] for Z = 5-6, and we find that our theoretical results agree with these experimental results within 1σ or 2σ . For Z = 9-10, a systematic deviation with 1σ between our results and Edlén's experimental results [14] is found.…”

XUV Fluorescence Detection of Laser-Cooled Stored Relativistic Ions

“…The ion beam was spatially overlapped with a counterpropagating laser beam on the same straight section where the XUV fluorescence detector is located. The revolution frequency of the ions was measured with a Schottky resonator at the 189th harmonic (∼244 MHz), while the emitted fluorescence photons were measured using the improved moveable in vacuo XUV detection system [8,9]. The principle of the XUV detector (shown in Figure 1 on the right) relies on the photoelectric effect and was successfully deployed in 2016 for laser spectroscopy of the 2 S 1/2 → 2 P 1/2 , 2 P 3/2 transitions in stored and cooled relativistic C 3+ ions [8].…”

“…The revolution frequency of the ions was measured with a Schottky resonator at the 189th harmonic (∼244 MHz), while the emitted fluorescence photons were measured using the improved moveable in vacuo XUV detection system [8,9]. The principle of the XUV detector (shown in Figure 1 on the right) relies on the photoelectric effect and was successfully deployed in 2016 for laser spectroscopy of the 2 S 1/2 → 2 P 1/2 , 2 P 3/2 transitions in stored and cooled relativistic C 3+ ions [8]. The XUV detector's geometry is designed to collect forward emitted photons, taking into account the relativistic boost which causes the fluorescence photons to be emitted in a 1/γ cone in the forward direction [10].…”