High-resolution photoemission spectra of the Si 2p level for freshly cleaved Si(111) reveal two additional core-level structures which were shifted relative to the bulk. The observed shifts were 0.59eV to lower and 0.3eV to higher binding energy, respectively. These shifted peaks, which vanished with increasing contamination of the surface, were shown to be directly correlated with reconstruction on the Si(111) 2 x 1 surface.

Core-Level Binding-Energy Shifts Due to Reconstruction on the Si(111) 2 x 1 Surface. S.Brennan, J.Stöhr, R.Jaeger, J.E.Rowe: Physical Review Letters, 1980, 45, 1414-8