Abstract
The emission spectra from a given adatom initial state are analyzed as a function of photon energy. We can classify the emission spectra into two classes according to the initial state. For initial states with no nodes, the emission spectra contain interference modulations sensitive to the adsorbate-substrate distance. For initial states with nodes, the spectra at low energies are dominated by a main peak which is independent of surface structure and which has its origin in the emission of a single adatom.