Comment on "Single Hole Dynamics in the CuO$_2$ Plane at Half Filling"

In a recent letter, Pothuizen et al. reported angle-resolved photoemission data on the single-layer insulating cuprate Sr_2CuO_2Cl_2. This comment addresses the issue whether it is possible to deduce an accurate value for the O 2p hopping integral $t_{pp}$ from these experiments, and also cautions against drawing conclusions concerning scattering mechanisms in the CuO_2 plane from a line-width analysis.