Glow discharge optical spectroscopy for microvolume elemental analysis

Glow discharge optical spectroscopy (GDOS) is an analytical technique whereby neutral sample atoms are sputtered into a glow discharge, excited by inelastic electron collisions, and decay emitting a characteristic luminescence which is monitored. We have shown that GDOS is capable of quantitative elemental analysis of microvolume solid samples and exhibits no evidence of ’’matrix effects’’. The sensitivity of GDOS for several different metallic and semiconducting elements has been determined and the variation in sensitivity for the elements studied is in the range of one order of magnitude. The present minimum detectable concentrations range from approximately 0.1 to 50 ppm for sputtering rates of 2 μg/sec and the possibility of reducing these detection limits seems quite good. Precipitated alloy samples studied by GDOS were found to exhibit radical changes in surface topography after short periods of sputtering. The precipitates sputtered slower than the bulk and formed protrusions above the sample surface. Surface topographical changes during sputtering appear to be the ultimate limit to GDOS depth resolution.