Quantitative SIMS Analysis Research Articles

Secondary-ion yields of rare earths

The intensities of the monatomic and monoxide secondary ions of rare earth elements (REEs) obtained by bombardment with a primary beam of O − ions have been measured for silicate glasses containing all fourteen REEs. Significant variations in secondary-ion yield are found among the REEs and these must be taken into account in quantitative SIMS analysis. The LTE model is not very effective in predicting REE ion yields and is handicapped by the lack of partition function data. The monoxide/atomic secondary-ion intensity ratios of REEs are unusually high and vary widely, the inter-element variation in the silicate glass matrix showing a quite close correlation with oxide bond energy. Measurements were also made on other samples including pure REEs, pure REE oxides and REE-aluminium alloys. Oxides give higher oxide/element ratios in the secondary-ion spectrum than either the metallic samples or the silicate glasses, the difference being greatest for the REEs with the greatest oxide bond energy.

An alternative to the relative sensitivity factor approach to quantitative SIMS analysis

AbstractMeasurements have been made of positive secondary ion currents from oxygen bombardment of glass standards, obtained either from NBS or specially prepared in this laboratory. By using one fitting parameter, the ionization temperature Ti, a semi‐quantitative analysis (accurate to within a factor of 2–3) is possible on any one of these standards. This approach, whilst achieving an accuracy comparable to that obtainable using relative sensitivity factors, does not restrict the analysis to those elements for which sensitivity factors are available. Further, change of sample matrix, which can alter sensitivity factors in a seemingly puzzling fashion, can easily be rationalized and accommodated through variation in Ti. Values of Ti for 16 binary oxides lie between 5500 and 9500 K. The Ti value for a more complex matrix can be estimated on a proportional basis from these binary oxide results.

Secondary ion energy spectra of polycrystalline transition metals and aluminium

Secondary ion energy spectra from polycrystalline Al, Sc, Ti, V, Cr, Fe, Ni, Cu, Hf, W and Au are presented, exhibiting a complex structure in the region 0–55 eV which is shown to be dependent on surface contamination levels. The design limitations present in existing ion energy and mass analysers, which have prevented the observation of these effects in the past, are defined and methods for their correction are suggested. The changing shape of the ion energy spectrum as a function of the local matrix and surface environment of the departing particle is shown to represent a fundamental difficulty for conventional quantitative SIMS analysis.

On the use of the saha-eggert equation for quantitative sims analysis using argon primary ions

Samples of known composition have been bombarded by Ar + ions. The resulting secondary ion mass spectra, obtained with two different types of SIMS instruments, were used to check the validity of the Saha-Eggert equation for the case of Ar + ion bombardment.