Spectroscopic study of the 4f76s2 8 S7/2∘ – 4f7(8S°) 6s6p(1P°) 8P5/2,7/2 transitions in neutral europium-151 and europium-153: absolute frequency and hyperfine structure

Abstract

We report on spectroscopic measurements on the 4f76s28S7/2∘−4f7(8S∘)6s6p(1P∘)8P5/2,7/2 transitions at 466.32 nm and 462.85 nm, respectively, in neutral europium-151 and europium-153. The center of gravity frequencies for the 151 and 153 isotopes for both transitions are reported for the first time using saturated absorption spectroscopy. For the 6s6p(1P∘)8P5/2 state, the center of gravity frequencies were found to be 642,894,493.3(4) MHz and 642,891,693.3(9) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to be A(151)=−157.01(3)MHz, B(151)=74.5(4)MHz and A(153)=−69.43(14)MHz, B(153)=191.0(26)MHz. These hyperfine values are all consistent with previously published results except for B(151) that has a small discrepancy. The isotope shift was found to be 2799.54(20) MHz, a small discrepancy with previously published results. For the 6s6p(1P∘)8P7/2 state, the center of gravity frequencies were found to be 647,708,930.6(6) MHz and 647,705,958.4(26) MHz for the 151 and 153 isotopes, respectively. The hyperfine constants for the upper state were found to be A(151)=−218.66(4)MHz, B(151)=−293.4(8)MHz and A(153)=−97.15(13)MHz, B(153)=−750(3)MHz. These values are all consistent with previously published results except for A(151) that has a small discrepancy. The isotope shift was found to be 2972.8(5) MHz, a small discrepancy with previously measured results.