Imaging TOF-SIMS for the surface analysis of silver halide microcrystals

Abstract

Photographic materials are interesting to gain insight in the general applicability of TOF-SIMS imaging. On the one hand this study was concentrated on the distribution of elements (in particular halides) and small molecular fragments such as SCN. Using a Ga + liquid metal ion gun the distribution of these compounds could be studied with high lateral resolution, up to 70 nm. Moreover by applying higher primary ion doses, the in-depth distributions of these compounds could be studied for thin conversion layers. On the other hand, the capability for imaging larger organic molecules (organic dyes) was studied. The achievable lateral resolution for this type of compounds is limited due to lower secondary ion yields. In order to overcome this problem specific elements such as fluorine can be introduced into the molecules, this allows direct imaging of the compound at the surface of silver halide microcrystals (using the fluorine label). Analyzing the samples with polyatomic primary ions can improve molecular identification, but at this moment imaging capabilities remain limited.