Jdependences of the isotope shift and hyperfine structure in Gd i 4f75d6s29D, 4f75d6s6p9D, and9Fterms

Isotope shifts of 16 transitions in 4${\mathit{f}}^7$5d6${\mathit{s}}^2$ ${(}^9$D)-4${\mathit{f}}^7$5d6s6p${(}^9$D${,}^9$F) of Gd i for the stable isotopes with A=152–160 were measured by atomic-beam laser spectroscopy. The hyperfine constants A and B of ${}_{}{}^{155}{}_{}{}^{}\mathrm{Gd}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Gd}$ in two ${}_{}{}^9{}_{}{}^{}$D terms and the ${}_{}{}^9{}_{}{}^{}$F term were determined. The single-electron hyperfine parameters ${\mathit{a}}_{4\mathit{f}}^{10}$ for the 4f electron and ${\mathit{a}}_{5\mathit{d}\mathit{s}}^{\mathit{k}}$ ${\mathit{k}}_{\mathit{l}}$,${\mathit{b}}_{5\mathit{d}\mathit{s}}^{\mathit{k}}$ ${\mathit{k}}_{\mathit{l}}$ for the 5d electron were deduced. The electric quadrupole moments Q of ${}_{}{}^{155}{}_{}{}^{}\mathrm{Gd}$ and ${}_{}{}^{157}{}_{}{}^{}\mathrm{Gd}$ were obtained to be 1.27(5)b and 1.36(6)b, respectively. The J dependences of the isotope shifts in two ${}_{}{}^9{}_{}{}^{}$D terms and the ${}_{}{}^9{}_{}{}^{}$F term were observed. The parameter ${\mathit{z}}_{5\mathit{d}}$ of the crossed-second-order effect for the ${}_{}{}^9{}_{}{}^{}$D term of 4${\mathit{f}}^7$5d6${\mathit{s}}^2$ was derived, and the value of ${\mathit{z}}_{5\mathit{d}}$/λ was obtained to be 134(4) MHz/${\mathrm{fm}}^2$. We confirmed that the field shift is dominant in the...