The Storing Matter technique: Application to PVC using Au and Ag collectors

The Storing Matter technique has been developed to perform quantitative surface analysis with high sensitivity. This technique consists in decoupling the sputtering of the specimen from the subsequent analysis step. In the recently developed prototype instrument, the sample surface is sputtered by an ion beam and the emitted particles are deposited at submonolayer level on a dedicated collector under UHV conditions. In a second step, the matter deposited on the collector is analyzed by SIMS in dynamic or static mode. The chemical nature of the collector surface is chosen with regard to the subsequent SIMS analysis (high or low work function to enhance positive or negative ionization, metallic overlayer for optimized organic information by cationization, etc.) by depositing thin films by electron beam evaporation. This paper presents the first results obtained on PVC samples with the Storing Matter prototype instrument. The chosen collector surfaces were Au and Ag, which are known to enhance cationization in static SIMS. The positive mass spectra obtained from Storing Matter deposits on these collectors were compared to those recorded on a PVC reference sample, on a PVC sample covered with a thin metallic overlayer, on a PVC thin film deposited on a metal substrate, and on the pristine collectors. This study showed that the Storing Matter technique allows for a clear identification of the PVC deposit on the Ag collector, while identification was impossible in the case of the Au collector due to a high degree of organic contaminations on the pristine collector. Copyright (C) 2010 John Wiley & Sons, Ltd.