The structures of 3 x 1 reconstructions on Si(111) and Ge(111) surfaces, as induced by the adsorption of alkali metals, were deduced on the basis of surface X-ray diffraction and low-energy electron diffraction data; combined with density functional theory. The 3 x 1 surface resulted mainly from the substrate reconstruction, and exhibited a new bonding configuration which consisted of consecutive 5-fold and 6-fold Si or Ge rings in <1¯10> projection; separated by channels which contained the alkali metal atoms.

L.Lottermoser, E.Landemark, D.M.Smilgies, M.Nielsen, R.Feidenhans, G.Falkenberg, R.L.Johnson, M.Gierer, A.P.Seitsonen, H.Kleine, H.Bludau, H.Over, S.K.Kim, F.Jona: Physical Review Letters, 1998, 80[18], 3980-3