The electronic energy levels of hydrogen adsorbed on three low-index planes of tungsten have been studied by a directional photoemission technique for coverages between 0.01 and 1 monolayer. A number of relatively sharp resonance levels are observed, which show half-widths down to 0.5 eV. For the (100) face, a single high-coverage state evolves from multiple low-coverage states, while on the (110) face two states appear to build up sequentially. No pronounced coverage dependence is observed for the (111) face.

• Received 30 April 1973

DOI:https://doi.org/10.1103/PhysRevB.8.4890