The isotope shifts of the 6 ${}_{}{}^2{}_{}{}^{}$${\mathit{S}}_{1/2}$–5 ${}_{}{}^2{}_{}{}^{}$${\mathit{D}}_{5/2}$ transition in ${\mathrm{Ba}}^{+}$ have been measured using the high-resolution laser spectroscopy of a single trapped ion. The shifts are measured among three even ${\mathrm{Ba}}^{+}$ isotopes, ${}_{}{}^{138}{}_{}{}^{}\mathrm{Ba}_{}^{+}{}_{}{}^{}$, ${}_{}{}^{136}{}_{}{}^{}\mathrm{Ba}_{}^{+}{}_{}{}^{}$, and ${}_{}{}^{134}{}_{}{}^{}\mathrm{Ba}_{}^{+}{}_{}{}^{}$. The results are ${\nu }_{138\mathrm{-}}$${\nu }_{136}$=-106.143(4) MHz and ${\nu }_{138\mathrm{-}}$${\nu }_{134}$=-38.455(15) MHz. This experiment gives a measurement of isotope shifts for a heavy atom. The results should provide a stringent test for the theoretical calculations of the isotope shifts of alkali-metal-like atoms.

• Received 16 January 1995

DOI:https://doi.org/10.1103/PhysRevA.51.4483