The Si(111)-(7 x 7) reconstruction was investigated by high-resolution core-level spectroscopy. A detailed line-shape analysis of spectra recorded over a wide photon energy range demonstrated the presence of four surface-derived components in the Si 2p line. These were attributed to the structural building blocks of the (7 x 7) structure through their relative intensities, evaluated for different photon energies in order to take photoelectron-diffraction effects into account, and on the basis of temperature-dependent changes in line shape that occurred in the (7 x 7)-(1 x 1) phase transition at around 1130K.

Correlation of Surface Core Levels and Structural Building Blocks for the Si(111)-7 x 7 Reconstruction through High-Resolution Core-Level Spectroscopy. J.J.Paggel, W.Theis, K.Horn, C.Jung, C.Hellwig, H.Petersen: Physical Review B, 1994, 50, 18686-9