Soft X-ray Emission Spectra (XES) from
C2H4/Cu(110) and C6H6/Cu(110)
have been obtained for two excitation energies, resonant and
non-resonant, and resolved in all three spatial components (x, y, z).
The one-step theory for resonant soft
X-ray spectroscopy and Raman scattering is extended to adsorbates on
metal surfaces and is
implemented within a Density Functional Theory (DFT) framework. The
calculations are performed for ethylene and benzene chemisorbed on
Cu(110) using cluster models (up to 86 Cu atoms) of the metal surface;
the calculations are performed for both resonant and non-resonant
excitation with the focus on the polarization and symmetry selectivity
and the role of channel interference. The molecular
mirror plane symmetry is maintained for the chemisorbed system, and for
the generated core hole, which leads
to an energy dependent symmetry and polarization
selectivity in the emission process. The
calculations and experiment show good agreement both with regard to
intensities and energy positions of the peaks.