SELECTIVITY, SPECIFICITY AND SENSITIVITY IN THE PHOTOIONIZATION OF SPUTTERED SPECIES

Resonance ionization of sputtered species has emerged as an exceedingly powerful technique for surface-compositional analysis and as a means to study a variety of fundamental aspects of the sputtering process. To deal with the problem of non- or near-resonant ionization, one needs to achieve the highest selectivity for photoionization of the species of interest relative to isobarically overlapping species by choosing a specific photoionization scheme tailored to that purpose. The present paper illustrates this point with several examples and helps point the way to still further improvements in detection sensitivity by minimizing non- or near-resonant ionization through detailed exploration of alternative photoionization schemes.