Title: Comment on "Laser cooling of $^{173}$Yb for isotope separation and precision hyperfine spectroscopy",
Abstract: We present measurements of the hyperfine splitting in the Yb-173
$6s6p~^1P_1^{\rm o} (F^{\prime}=3/2,7/2)$ states that disagree significantly
with those measured previously by Das and Natarajan [Phys. Rev. A 76, 062505
(2007)]. We point out inconsistencies in their measurements and suggest that
their error is due to optical pumping and improper determination of the atomic
line center. Our measurements are made using an optical frequency comb. We use
an optical pumping scheme to improve the signal-to-background ratio for the
$F^{\prime}=3/2$ component.