We report on use of cavity ring-down spectroscopy (CRDS) as a means to detect and quantify ion sputtering of refractory metal species. CRDS measurements are made with a neodymium:YAG-pumped optical parametric oscillator laser system in the 375-400 nm region. CRDS sputtering measurements are presented for argon ions incident on iron, aluminum, molybdenum, and titanium. The measurements are based on absorption from fine-structure levels of the electronic ground-state multiplets. For each species, characteristic spectra are provided, the dependence of sputtered particle number density on the beam current is examined, measured densities are compared with a sputter model, and detection limits are determined. For iron, aluminum, and titanium we probe multiple fine-structure levels within the ground-state multiplet and obtain information on their relative populations.

We report sputtering studies of multi-component spacecraft materials. We employ two complementary diagnostic methods: weight loss measurements and cavity ringdown spectroscopy (CRDS). The weight loss measurements provide total sputter yields as a function of ion energy and incidence angle. We present sputter yields from weight loss measurements for xenon ion sputtering of molybdenum, quartz, boron nitride, and kapton. The CRDS provides species-specific sputtering data (number density and velocity) as well as information on the differential (angular) sputtering distributions. We present CRDS results for the sputtering of molybdenum (from a molybdenum sample), and demonstrate measurements of multi-component materials by measuring the sputtering of chromium, iron, and molybdenum from inconel 718.