Hidden surface states on Ni(111) pristine and hydrogen passivated surfaces
Lobo-Checa, Jorge1; Okuda, Taichi2; Hengsberger, Matthias1; Patthey, Luc1; Greber, Thomas1; Blaha, Peter3; Osterwalder, Juerg1
1Switzerland;
2Japan;
3Austria

By means of angle resolved photoemission, we have investigated the existence of new surface related states on the pristine and hydrogen saturated Ni(111) surface. Normal emission spectra at room temperature were recorded as a function of the photon energy. A new hidden surface resonance has been found on the clean Ni(111) surface at a binding energy of 1.19 eV completely masked by the Λ1 bulk d-band. The existence of this resonance is in agreement with the DFT calculations presented here. On the other hand, a new surface state related to the hydrogen adsorbed on the surface has been found at a binding energy of 0.22 eV. Under hydrogen exposure, the hydrogen induced surface state intensity grows at the same rate as the three other surface states of the clean Ni(111) decrease.
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