Probing the Local Density of States of Metal Surfaces by Deexcitation of Metastable Noble-Gas Atoms

Resonance ionization followed by Auger neutralization is the mechanism for deexcitation of metastable noble-gas atoms (He, Ne, Ar) at metal surfaces which are either clean or covered with "small" atomic adsorbates and whose work function is {} 4.5 eV. The energy distributions of the emitted electrons reflect the self-convolution of the local density of states of the outermost atomic layer and thus provide a spectroscopic technique with extreme surface sensitivity as demonstrated with Pd(111) and Cu(110) surfaces.