SPUTTER YIELDS AND EROSION RATES FOR LOW-ENERGY ION-BOMBARDMENT OF MULTIELEMENTAL POWDERS

For depth-resolved analysis of particulate material such as pigments, ceramic powders or environmental microparticles with secondary neutral mass spectrometry (SNMS), erosion rates and sputter yields of 16 powd ers, including salts, metal and nonmetal oxides, have been measured to provide data for the conversion of sputter time into depth values. Fo r that purpose a new gravimetric method was developed, which allows th e measurement of depth propagation within particles even for bad elect rical conductors. With about 1 mA/cm(2) of 400 eV argon ions for the 1 6 powders an average sputter yield of Y = 1.2 and a mean erosion rate of z = 0.4 nm/s were measured. In spite of the chemical variety of the powders a standard deviation of only 40% was observed, which gives th e relative error for a depth calibration in case of an unknown analyte . Comparison between compact and particulate samples showed the powder erosion data to be valid within a factor of 2 even for compact sample s with flat surfaces. No correlation between the heat of atomization a nd the sputter yield could be recognized.