Author/Authors :
Allegretti، نويسنده , , F. and Bussolotti، نويسنده , , Jack F. and Woodruff، نويسنده , , D.P. and Dhanak، نويسنده , , V.R. and Beccari، نويسنده , , M. and Di Castro، نويسنده , , V. and Betti، نويسنده , , M.G. and Mariani، نويسنده , , C.، نويسنده ,
Abstract :
The local adsorption geometry of benzenethiolate in the ordered c(2 × 6) phase on Cu(1 0 0) has been investigated by a combination of S K-edge near-edge X-ray absorption fine structure (NEXAFS), normal incidence X-ray standing waves (NIXSW) and S 1s scanned-energy mode photoelectron diffraction (PhD). NEXAFS and PhD show that the molecular plane is tilted from the surface normal by 20 ± 15°, while NIXSW clearly identifies the S head-group as occupying the four-fold coordinated hollow sites. PhD shows the S atoms lies 1.34 ± 0.04 Å above the outermost Cu atomic layer, leading to a Cu–S bondlength of 2.25 ± 0.02 Å. The combination of the PhD and NIXSW results shows the Cu surface layer has an outward relaxation of 0.15 ± 0.06 Å. Possible origins for this large adsorbate-induced relaxation are discussed.
Keywords :
X-ray standing waves , Photoelectron diffraction , Copper , Benzenethiol , Chemisorption , surface structure , NEXAFS
