Inversion of the core level shift between surface and subsurface atoms of the iridium (100)(1 × 1) and (100)(5 × 1) surfaces

Abstract In contrast to what is commonly accepted, electronic structure calculations show that the core levels (S 1 , S 2 ) associated with the surface and first underlayer atoms can be displaced in opposite directions in energy with respect to the bulk level ( B ). This is fully confirmed by experiments performed on the 4f 7 2 level of the Ir(100) surface, both in the unreconstructed (1 × 1) and reconstructed (5 × 1) case.