Electronic structure of adsorbates from core-level shake-up spectra:N2on Ni(100)

The shake-up and shake-off spectrum for ${\mathrm{N}}_2$ adsorbed on Ni(100) has been recorded up to 75 eV above the 1s lines. Using photoelectron-diffraction effects, the complete satellite spectra from the two inequivalent nitrogen atoms have been separated. The two spectra are significantly different which gives information about the character of the shake-up states. The proposed interpretation is further supported by a comparison with the C-1s shake-up spectrum for adsorbed CO. More than 80% of the spectral strength is contained in the satellites.