RBS studies of the absolute coverage of Cs on the Si(111)-7 x 7 surface

The absolute saturation coverage of Cs adsorbed on the Si(1 1 1)-7 x 7 surf ace at room temperature has been measured using Rutherford backscattering s pectrometry. At saturation, coverage is 0.51 +/- 0.02 monolayers (ML) where 1 ML = 7.83 x 10(14) atoms/cm(2). This value constrains proposed ordered s tructural models by placing a strict upper limit on the absolute coverage o f the first Cs layer adsorbed on Si(1 0 0) at room temperature. Proposed st ructural models with lower coverages of ordered Cs must include substantial disordered components. (C) 2001 Elsevier Science B.V. All rights reserved.