SURFACE EXAFS STUDY OF (SQUARE-ROOT 7 X SQUARE-ROOT 7) R19.1-DEGREES S/CU(111)

The surface local structure of (surd;;7 × surd;;7)R19.1° S/Cu(111) was studied by the polarization-dependent surface EXAFS method. The results clearly indicate the existence of two or more types of copper coordinations around sulfur atoms and they are incompatible with the previous models proposed by LEED experiments. In order to explain the surface EXAFS results, a new model is proposed, where the Cu(111) surface layer is drastically reconstructed with both lateral and vertical movements, and the sulfur atoms are located at three types of 3-fold hollow sites of the reconstructed surface. © 1990 IOP Publishing Ltd.