Detection of sputtered metals with cavity ring-down spectroscopy.
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.
Yalin
A P
AP
Department of Mechanical Engineering, Colorado State University, Fort Collins, Colorado 80523-1374, USA. ayalin@engr.colostate.edu
Surla
V
V
Butweiller
M
M
Williams
J D
JD