A report was given of W(4ƒ) surface core level shifts which yielded new information on the energetics of the W(100) (1 x 1) → c(2 x 2)H phase transition. At small hydrogen coverages, two co-existing surface core levels from atoms on normal lattice sites and from atoms in reconstructed domains were found. These surface levels were shifted to smaller binding energy (towards EF) by 0.35 and 0.13eV relative to the bulk level, respectively. The most stable configuration was obtained at a fractional coverage θH of ≈0.2, at which all surface atoms were shown to be paired with neighbouring atoms in the surface plane.

Hydrogen-Induced Reconstruction of the W(100) Surface, Studied by Surface Core Level Spectroscopy. J.F.van der Veen, F.J.Himpsel, D.E.Eastman: Solid State Communications, 1981, 40[1], 57-60