Saturated fluorescence spectroscopy measurement apparatus based on metastable Li+ beam with low energy

Abstract

The apparatus for fluorescence spectroscopy measurement is developed to determine the fine structure (FS)/hyperfine structure (HFS) splittings of 1s2p 3PJ(J=0,1,2) states of Li+. The instrument is composed of a low energy Li+ ion source and a saturated fluorescence spectroscopic probing system. A low energy Li+ ion source, containing 1.8(7)% of 1s2s 3S1 metastable ions with an energy of ∼500 eV, is obtained by an electron bombardment process. The ion current can stay more than 250 h with the variation of ∼0.3%, and the divergence of ion beam is ∼0.5 mrad. The symmetric profile of Lamb dip signals of 1s2s 3S1−−1s2p 3PJ transitions with linewidths of ∼50 MHz are obtained after subtracting Doppler background from the saturated fluorescence signals. A back-and-forth scan method is adopted to determine the FS/HFS splittings of 1s2p 3PJ states. Under these conditions, as a preliminary test, several splittings of 7Li+ are measured. The statistical uncertainties of the FS/HFS splittings are estimated to be less than 50 kHz, and the results are one order of magnitude better than previous results. The apparatus is feasible to precisely determine the splittings of energy levels of alkali and alkaline earth ions.

Measurement of hyperfine structure and the Zemach radius in $\rm^6Li^+$ using optical Ramsey technique

“…The resulting improved measurements of the hfs intervals in the 2 3 S 1 and 2 3 P J states of 6 Li + are now sensitive to QED effects of order mα 7 . The derived Zemach radius of 2.44(2) fm for the 6 Li nucleus is in sharp disagreement with the value 3.71 (16) fm obtained from models of the nuclear charge and magnetization distributions [4], in contrast to the good agreement for the case of 7 Li. It seems clear that the nuclear structure of 6 Li is anomalous and requires further study.…”

“…1 for the energy level scheme of 6 Li + . These two values are consistent with each other, but in disagreement with the value 3.71 (16) fm derived from simple nuclear models [4]. The present work confirms the previous discrepancy and reduces the uncertainty in R em by a factor of 4, with the dominant source of uncertainty being the δ QED term.…”

“…In our previous work [6], two values of R em were obtained from two hfs intervals in 2 3 S 1 , which was 2.40 (16) fm from F = 0 − F = 1 interval and 2.47(8) fm from F = 1 − F = 2 interval, see Fig. 1 for the energy level scheme of 6 Li + .…”

“…2. A continuous beam of 2 3 S 1 metastable 6 Li + ions is produced by an ion beam source [16]. Briefly, heating a bulk lithium sample (95% 6 Li, Sigma-Aldrich) in an oven produces an effusion beam of neutral lithium atoms, which intersects a focused electron beam.…”

Lamb-Dip Laser-Induced Fluorescence Spectroscopy in a Supersonic Plasma Jet for Isotope Identification

“…A Lamb-dip is a Doppler-free spectrum caused by the hole-burning effect that can then distinguish a narrow nonhomogeneous broadening for each isotope. [18][19][20][21] In addition, the fluorescence signal is amplified due to the double beam. When the plasma jet is used under low-pressure conditions, the pressure broadening effect is negligible.…”