The crystallography of the (100)-c(8 x 2)Ga surface, prepared by simultaneous cycles of Ar ion bombardment and annealing at 825K, was determined by performing low-energy electron diffraction I-V analyses. It was found that a model which involved 3 adjacent dimers and a dimer vacancy yielded the best fit. The main feature of the corresponding structure was the presence of 2 different types of Ga dimer at the surface. The dimer in the middle was fully dimerized (dGa-Ga = 0.213nm), while the dimerization of the Ga atoms in both outer dimers was much more mild (dGa-Ga = 0.345nm).

J.Cerdá, F.J.Palomares, F.Soria: Physical Review Letters, 1995, 75[4], 665-8