Second harmonic response of the Si(111)7 × 7 surface

► Experimental SHG spectra of a clean Si(111)7 × 7 surface from 0.8 eV to 2.5 eV. ► Microscopic SHG semi-empirical tight binding calculation. ► Good agreement between theory and experiment. ► Layer-by-layer analysis of the resonances confirms their surface or bulk character.