Isotope shifts at 1.28 μm in Pb

Abstract

The isotopic shift of the 6${\mathit{p}}^{2}$ $^{3}$${\mathit{P}}_{0}$\ensuremath{\rightarrow}6${\mathit{p}}^{2}$ $^{3}$${\mathit{P}}_{1}$ (1.28 \ensuremath{\mu}m) magnetic-dipole transition in Pb, which had been previously estimated incorrectly in the literature, has been measured, together with the magnetic hyperfine constant of the $^{3}$${\mathit{P}}_{1}$ level in $^{207}\mathrm{Pb}$. The shifts of the $^{206}\mathrm{Pb}$ and $^{207}\mathrm{Pb}$ lines from the $^{208}\mathrm{Pb}$ position are \ensuremath{\delta}(206--208)=220.4(15) MHz and \ensuremath{\delta}(207--208)=138.0(17) MHz, and the hyperfine constant A(6${\mathit{p}}^{2}$ $^{3}$${\mathit{P}}_{1}$)=-2388.2(45) MHz. Inclusion of the shifts in calculated optical rotation line shapes removes long-standing discrepancies between theory and experiment, which have limited the precision of parity-nonconservation measurements in Pb.