Comment on ‘‘Adsorption of ${\mathrm{C}}_{60}$ on Ta(110): Photoemission and C K-edge studies’’

In a recent paper [Phys. Rev. B 48, 15 457 (1993)] Ruckman et al. characterized ultrathin ${\mathrm{C}}_{60}$ films on a Ta(110) surface by photoemission and C K-edge studies. They concluded that some fraction of the fullerene overlayer decomposes on the clean metal surface resulting in a thin layer of carbon between the assembled film and the metal substrate. In this Comment we argue that there is not enough experimental evidence to sustain this interpretation. Their experimental results can be interpreted by a chemisorbed first monolayer without inferring the formation of a thin carbon layer at the interface. Furthermore, their proposed alignment of the ${\mathrm{C}}_{60}$ π and ${\mathrm{\pi }}^{\mathrm{*}}$ energy levels is not correct.