Angle-resolved photoemission study of the electronic structure of chemisorbed hydrogen on Ni(111)

The electronic structure of hydrogen chemisorbed on Ni(111) has been studied using angle-resolved polarization-dependent photoelectron spectroscopy with synchrotron radiation. For coverages from ∼0.01 to ∼0.1 monolayer, we observe a shift of the $p_Z$-type Ni(111) surface state towards increased binding energies. At saturation coverage, direct transitions from $\mathrm{sp}$-type bands are enhanced, whereas $d$-like interband transitions remain unchanged. We observe no split-off hydrogen-derived state. Since hydrogen is observed to bond only to $\mathrm{sp}$-type orbitals, a simple metal (jellium) model is qualitatively applicable and can account for the lack of a split-off adsorbate state.