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 S-1(0)-P-3(1) 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 Ba-137 and Ba-135 for this transition have been extracted from the experimental results: a((137) Ba) = 1149.9(1.0) MHz, b(Ba-137) = -41.6(0.5) MHz, a((135) Ba) = 1028.0(1.0) MHz, b(Ba-135) = -27.5(0.5) MHz. The measured IS results with the reference isotope Ba-138 are 183.7(1.0) MHz (Ba-137-Ba-138), 108.5(0.3) MHz (Ba-136-Ba-138) and 218.9(1.0) MHz (Ba-135-Ba-138). Our IS measurements are in good agreement with the previous experiments. The field shift (FS) factor F-k and the mass shift (MS) coefficient, Delta K-MS 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 nuclear structure of the barium isotopic nuclei.