Clock and inter-combination line frequency separation in ${}^{171}$Yb

We have carried out concurrent optical frequency measurements of the $(6s^2){}^1{S}_0-(6s6p){}^3{P}_1$ ($F=\frac{3}{2}$) and $(6s^2){}^1{S}_0-(6s6p){}^3{P}_0$ transitions in ${}^{171}$Yb, and in so doing have determined the frequency separation between the ${}^3{P}_0$ ($F=\frac{1}{2}$) and ${}^3{P}_1$ ($F=\frac{3}{2}$) levels with an uncertainty in the ppb range. The knowledge of this frequency interval will aid experiments relying on the ${}^1{S}_0-{}^3{P}_0$ line in ${}^{171}$Yb and ${}^{173}$Yb without access to highly accurate frequency standards.