Experimental determination of the field shift factor and the mass shift coefficient for the 1S0–3P1 spin-forbidden transition at 791 nm in neutral barium

The experimental measurements of the isotope shifts (ISs) for the 1S0–3P1 spin-forbidden transition at 791 nm in neutral barium have been carried out with a thermal barium atom beam. The hyperfine structure (HFS) constants a and b of the odd isotopes 137Ba and 135Ba for this transition have been extracted from the experimental results: a(137Ba) = 1149.9(1.0) MHz, b(137Ba)= −41.6(0.5) MHz, a(135Ba) = 1028.0(1.0) MHz, b(135Ba) = −27.5(0.5) MHz. The measured IS results with the reference isotope 138Ba are 183.7(1.0) MHz (137Ba–138Ba), 108.5(0.3) MHz (136Ba–138Ba) and 218.9(1.0) MHz (135Ba–138Ba). Our IS measurements are in good agreement with the previous experiments. The field shift (FS) factor Fk and the mass shift (MS) coefficient ΔKMS for this spin-forbidden transition have be determined experimentally as −3.19(4) GHz ⋅ fm−2 and −242(20) GHz ⋅ amu, respectively. The results provided herein could be used for further checks theoretically and experimentally, and could also contribute to the study on the nuc...