Reconstruction of a Ni (110) surface under the influence of adsorbed hydrogen atoms could proceed in two different ways: Below 180K, a 2 x 1 lattice-gas structure with θH = 1.0 transformed cooperatively into a 2-dimensional 1 x 2 structure by additional uptake of hydrogen up to θH = 1.5. At higher temperatures, activated local transformation into a more stable one-dimensional structure started already at low coverages.

Dual Path Surface Reconstruction in the H/Ni (110) System. K.Christmann, V.Penka, R.J.Rehm, F.Chehab, G.Ertl: Solid State Communications, 1984, 51[7], 487-90