銅クラスター上へのエチルザンセートイオンの化学吸着と酸素の影響

金属・鉱物に対する捕収剤・抑制剤の吸着 (第1報)

抄録

The extended Huckel molecular orbital method has been applied to the adsorption of ethylxanthate (EX^-) on Cu clusters of up to 13 atoms with (100) and (111) planes. The calculated values of the simulated Cu cluster are in good agreement with the empirical ones of copper metal in its electronodensities and band widths. The EX^- adsorption on copper is rather chemical than physical. Although EX^- outside a distance 4 Å from copper surface does not have any great effect on its atom populations or atomic bond pgpulation, all the above populations change as EX^- comes close to the Cu surface. These change is considerable at distances 2 Å and 3 Å from the Cu surface due to the strong mutual interaction between EX^- and Cu clusters. Electrons are in main transferred from the two sulfur atoms of EX^- to Cu clusters, and then the new bonds formed between two sulfur atoms and copper atoms play a great role for binding EX^- to the Cu surface with increasing their strength as the distance decreases. The main contribution to these bond is due to the 4sp orbitals of copper than due to the 3d orbitals of copper. Oxygen effect on chemisorption of EX^- on Cu clusters indicates that the adsorption system at low coverage of oxygen on Cu surface is more stable only to adsorb EX^- on the Cu surface and it becomes less stable at high coverage of oxygen on the Cu surface.