Effectiveness of atomic and polyatomic primary ions for organic secondary ion mass spectrometry

With the increased application of polyatomic primary ions for organic secondary ion mass spectrometry, a method to compare the performance of the various available projectiles is needed. In this work, primary ion performance was evaluated based on analyte-specific secondary ion yield, the amount of fragmentation, and the amount of metastable decay induced by each primary ion. These measurements were used to construct a projectile efficiency number for each primary ion applied to a specific analyte. An organic acid, phospholipids, and alkyl sulfates, prepared as multilayer and monolayer surfaces were analyzed with various atomic and polyatomic primary ions. It was found that polyatomic primary ions are best suited for multilayer organic samples whereas atomic primary ions are most effective for monolayer organic samples. Results are compared to other studies that measure the ion formation efficiency of various primary ions.