表面EXAFSによるNiステップ面上のP, S, Clの吸着構造の研究

概要

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The local structures of phosphorus, sulfur and chlorine adsorbed on a Ni (7 9 11) stepped surface were investigated by using the SEXAFS and LEED method. At the initial stage of chemisorption, S and P adsorb preferentially on the step site. S adsorbs on the step 4-fold site first, then on the terrace 3-fold site. Adsorption of P causes the reconstruction of the step 4-fold site due to the strong interaction with a Ni atom in the "second" layer. At 0.1 ML the adsorption of P induces the facetting of Ni (7 9 11) surface. On the contrary, Cl adsorbs mainly on the terrace site. Even at saturated coverage, there are few Cl atoms adsorbed on the step site. The adsorption behaviors of these elements seem to be related to their ionicity or covalency. This study indicates that the adsorbate tends to have a strong interaction with the step site as the covalency of the adsorbate increases. The longer bond distances of S and P adsorbed on the step site also indicate that the large electron transfer from Ni to adsorbates occurs in the S or P atoms adsorbed on the step 4-fold site. This also suggests that the electron-rich state of the stepped surface is localized on steps and the electronic structure of the terrace is almost the same as that of planar surfaces.
社団法人日本分析化学会の論文
1995-08-05