Comparison of Ga+ and SF5+ primary ions for the molecular speciation of oxysalts in static secondary ion mass spectrometry (S-SIMS)

Abstract

Speciation of inorganic compounds by means of static secondary ion mass spectrometry (S-SIMS) aims at deriving the molecular composition of the analyte in the solid. The recent use of polyatomic primary ions, instead of the traditionally applied monatomic or diatomic projectiles, potentially offers an increase in secondary ion intensity and an increase in molecular specificity. This paper focuses on the comparison of SF₅⁺ and Ga⁺ primary ion bombardment for the molecular speciation of inorganic oxysalts. The polyatomic primary ions are found to increase the total ion yield by a factor of 4–10. Furthermore, the relative intensities of the most structure-specific signals are increased in comparison with the low m/z peaks under SF₅⁺ bombardment relative to Ga⁺. Although the formation of oxide fragments is promoted with polyatomic projectiles, the mass spectra significantly gain in information concerning the molecular specificity.