Fragmentation of polystyrene during sputter deposition in the storing matter instrument

Abstract

The storing matter technique has been developed to get easier quantification in secondary ion mass spectrometry (SIMS) by decoupling the sputtering step from the analysis step. First, the matter is deposited in the submonolayer range on a collector that is analysed next by SIMS. Most work on the storing matter technique has been carried out for inorganic samples. The technique has also been applied successfully to organic samples. In this work, the fragmentation of polystyrene (PS) molecule deposited on silver (Ag) during storing matter deposition is investigated using static SIMS analysis with Bi3+ clusters. The fragmentation of PS at different coverages is studied by calculating the ratios of large‐to‐small peak intensities of fingerprint spectra. These ratios are compared with those obtained previously by the storing matter technique using Ar+ as analysis beam in time‐of‐flight‐SIMS. Different degrees of fragmentation are observed with varying coverage, suggesting different sticking factors of fragments on the collector. Compared with Bi3+, the Ar+ projectile produces a higher amount of large fragments and is found to be better suited for the analysis of PS deposits on silver collectors. In both situations, C7H7+ is the major fragment in the mass spectra. Copyright © 2014 John Wiley & Sons, Ltd.