  The electronic structure of artificial Mn atom arrays on Ag(111) is
characterized in detail with scanning tunnelling spectroscopy and spectroscopic
imaging at low temperature. We demonstrate the degree to which variations in
geometry may be used to control spatial and spectral distributions of surface
state electrons confined within the arrays, how these are influenced by atoms
placed within the structure and how the ability to induce spectral features at
specific energies may be exploited through lineshape analyses to deduce
quasiparticle lifetimes near the Fermi level. Through extensive comparison of
$dI/dV$ maps and spectra we demonstrate the utility of a model based upon
two-dimensional s-wave scatterers for describing and predicting the
characteristics of specific resonators.
