The surface vibrational modes of atomic hydrogen adsorbed on W (100), observed by electron-energy-loss spectroscopy in off-specular directions, indicate bridge bonding at all coverages. The vibrational frequencies show a dependence on the W-H-W bond angle which changes due to reconstruction of the tungsten lattice. The results indicate a W(100) c(2 x 2)H low-coverage β2 phase consisting of atoms occupying bridge sites on a (√2 x √2)R45° reconstructed substrate similar to the clean crystal surface at low temperatures.

Hydrogen-Adsorption-Induced Reconstruction of Tungsten (100): Observation of Surface Vibrational Modes. M.R.Barnes, R.F.Willis: Physical Review Letters, 1978, 41, 1729-33