Reducing the Matrix Effect in Molecular Secondary Ion Mass Spectrometry by Laser Post-Ionization

Abstract

Strategies to reduce and overcome matrix effects in molecular Secondary Ion Mass Spectrometry (SIMS) are investigated using laser based post-ionization of sputtered neutral organic molecules released under C60+ bombardment. Using a two-component multilayer film similar to that employed in a recent VAMAS interlaboratory study, SIMS depth profiles of the protonated and deprotonated quasi-molecular ions of two well-studied organic molecules, Irganox 1010 and Irganox 1098, were measured along with that of the corresponding neutral precursor molecules. When compared to composition dependent ionization probability changes of the secondary ions, the resulting profiles are much improved. We demonstrate that detection of neutral molecules via laser post-ionization yields significantly reduced matrix effects when compared to SIMS depth profiles in both positive and negative secondary ion mode. These results suggest that this approach may provide a useful pathway for acquiring depth profiles from complex organic sam...