Chemically resolved structure of the surface.
The structure and chemical states of the Sn/Ge(111) surface are characterized by x-ray standing waves combined with photoemission. For the room temperature square root 3xsquare root 3 phase two chemical components, approximately 0.4 eV apart, are observed for both Sn 3d and 4d core levels. Our model-independent, x-ray standing wave analysis shows unambiguously that the two components originate from Sn adatoms located at two different heights separated vertically by 0.23 A, in favor of a model composed of a fluctuating Sn layer. Contrary to the most accepted scenario, the stronger Sn 3d and 4d components, which appear at the lower binding-energy sides and account for 2/3 of the Sn adatoms, are identified to be associated with the higher Sn position, manifesting their filled valence state character.
Lee
Tien-Lin
TL
European Synchrotron Radiation Facility, Boîte Postale 220, F-38043 Grenoble Cedex 9, France.
Warren
Samantha
S
Cowie
Bruce C C
BC
Zegenhagen
Jörg
J