Comment on 'Determination of interface states for CaF sub 2/Si (111) from near edge X-ray absorption measurements'.

In a recent Physical Review Letter Himpsel et al. reported a photoabsorption study of the Ca 2p and F 1s absorption edges for a new monolayers of CaF sub 2 epitaxially grown on Si(111). A model for the CaF sub 2/Si(111) interface structure was derived from the interpretation of these absorption spectra. In this comment, we show that the peaks observed by these authors in the Ca L sub (2,3) spectrum are unrelated to the interface and the model for the geometrical structure do not follow from their experiment. For internal information only, we include a copy of Himpsel et al.'s Letter.