The Storing Matter technique applied to polystyrene: a study of different methods to enhance Ag‐cationization

Abstract

AbstractThe Storing Matter technique is derived from secondary ion mass spectrometry (SIMS) and consists in decoupling the sputtering of the specimen from the analysis step. In a dedicated prototype instrument, the sample surface is bombarded by an ion beam, and the sputtered particles are deposited at sub‐monolayer level onto a collector. In a second step, this deposit is analyzed by SIMS (static or dynamic). In this work, we applied the Storing Matter technique to different types of polystyrene (PS) samples: a layer of PS spin‐coated on a silicon wafer, the same sample covered with a thin Ag coating and a thin PS layer on an Ag substrate. These samples were sputter‐deposited onto Si and Ag collectors in the Storing Matter prototype instrument. These deposits as well as the initial PS‐based samples were analyzed by time‐of‐flight‐SIMS conditions in positive mode. We compared the intensities of Ag‐cationized oligomers for the different sample/collector combinations. The abundance and the intensities of Ag‐cationized PS fragments detected in a Storing Matter deposit depend more strongly on the collector material than on the sample configuration used for sputter‐deposition. For the deposits on Si collectors, almost no Ag‐cationized peaks were detected, although such species are present in the positive mass spectra recorded directly on the Ag‐containing PS samples. In the case of Ag collectors, Ag‐cationized adducts were detected up to m/z = 1500. It seems that their abundance is mainly determined by the sputtering efficiency of large fragments during the sputter‐deposition step. Copyright © 2012 John Wiley & Sons, Ltd.