Geometry-Dependent Si(2p) Surface Core-Level Excitations for Si(111) and Si(100) Surfaces Himpsel, F. J. ; Heimann, P. ; Chiang, T. -C. ; Eastman, D. E. Abstract Publication: Physical Review Letters Pub Date: June 1981 DOI: 10.1103/PhysRevLett.46.1602.2 Bibcode: 1981PhRvL..46.1602H