Properties of C84 and C24H12 Molecular Ion Sources for Routine TOF-SIMS Analysis.

C84+ and coronene (C24H12+) have been studied as primary ions for use in secondary ion mass spectrometry. A representative range of samples has been used to compare the effectiveness of each primary ion with the existing C60+, Au+, and Au3+ primary ions. It was found that C84 is the most effective primary ion providing higher secondary ion yields and a high molecular to fragment ion ratio. Coronene had a performance similar to C60. Coronene and C60 primary ions were also used to extend a previous study of matrix suppression/enhancement effects. The C60 was found to ameliorate this effect, possibly due to the increase in protonation in polyatomic sputtering, and coronene was found to further reduce suppression showing evidence of a chemical effect. [ABSTRACT FROM AUTHOR]