Photoemission study of the modification of the electronic structure of transition-metal overlayers on TiO_2 surfaces Ⅱ. Cr on TiO_2(001)

摘要

The electronic states of the Cr overlayers on TiO_2(001) surfaces have been investigated using angle-resolved and resonant photoemission spectroscopy with synchrotron radiation. At lower coverages, Cr deposition on TiO_2(001) creates two well separated in-gap emissions due to the formation of surface Ti~(3+) (3d~1) ions and Cr~(3+) (3d~3) ions. At higher coverages, the in-gap emission is developed into the 2-peak-structure emission of Cr 3d character. The corresponding state is considered to be of metallic nature from the viewpoint of the high ability of oxygen adsorption, but has no Fermi edge, indicating a possibility of forming small Cr clusters on TiO_2(001) at this stage.