Subkilohertz absolute-frequency measurement of the 467-nm electric octupole transition in171Yb+

The ${}^2{S}_{1/2}{\mathrm{}(F=0\mathrm{})\mathrm{}}^2{F}_{7/2}{(F=3,m}_F=0)$ transition at 467 nm in a single trapped, laser-cooled ion of ${}^{171}{\mathrm{Yb}}^{+}$ has been measured to be $f_{{\mathrm{Yb}}^{+}}=642\mathrm{}121496771.26\left(23\right)\mathrm{}\mathrm{kHz}$ using a femtosecond laser frequency comb generator. The measurement is limited by measurement statistics and by the ac Stark shift, both related to the 4.5 kHz linewidth of the probe laser at the time. The systematic shifts of the transition, including ac Stark, second-order Zeeman, quadrupole, and blackbody shifts, have been evaluated.