A surface elemental-analysis technique, ionization spectroscopy, is described and the characteristics of ionization spectra for contaminated vanadium, nickel, palladium, and molybdenum surfaces are examined. The minimum energies required to ionize the core shells of surface atoms, determined from ionization spectroscopy, are demonstrated to identify those elements. Ionization spectra are shown to be somewhat sensitive to the chemical state of the elements. It is concluded that combined Auger and ionization spectroscopy, using the same instrument, can yield improved analysis of surfaces.