Date of Original Version
We have carried out a back reflection x-ray standing-wave investigation to study the adsorbate-substrate bond length and bonding site for the system Rb/Cu(111). Our low-energy electron diffraction study showed an ordered (2×2) phase for one monolayer of Rb on Cu(111) (θ=0.25). By measuring both the (111) and (111¯) Bragg reflections at this coverage, we determine the Rb adsorption to be in the top site. We observe a high degree of order in the Rb overlayer perpendicular to the surface, with large disorder parallel to the surface.
X. Shi, C. Su, D. Heskett, L. Berman, C. C. Kao, and M. J. Bedzyk. (1994). "Adsorption-site investigation of Rb/Cu(111) using the x-ray standing-wave method." Physical Review B, 49(20), 14638. Available at: http://dx.doi.org/10.1103/PhysRevB.49.14638