LEED and STM study of Cs on Cu(211)

A low-temperature (25 K) STM study of Cs adsorption on Cu(211) indicates th at Cs forms variable-density structures which align along the step edges of the Cu(211) surface. The density of the overlayer increases with Cs covera ge, forming a quasihexagonal c(2 x 2) structure at a coverage of 0.17. A dy namical LEED study of that structure at 130 K indicates that the Cs atoms a re adsorbed on top of the Cu atoms in the center of the terraces, with a Cs -Cu nearest-neighbor distance of 3.56 +/- 0.04 Angstrom. This structure is accompanied by a significant rumpling of the Cu(211) surface.