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 C 60 + bombardment. Using a twocomponent 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 samples with improved capabilities for quantitation.

Reducing the Matrix Effect in Organic Cluster SIMS Using Dynamic Reactive Ionization

“…The matrix effect is weak. The fact that both values of Ξ are nearly identical (except for the sign) indicates that there is a constant RSF between the two components, leading to a linear correlation between both signals as shown elsewhere [28]. …”

A concise tutorial review of TOF-SIMS based molecular and cellular imaging

“…[128][129][130] Other studies used multilayer Irganox standard samples to calibrate the sputtering efficiency as a function of z height and determine a depth scale. [131][132][133] These Irganox standard samples are composed of a given succession of various layers of known compounds. The composition as well as the distance between the layers is known and this information is used to calibrate the z-scale and, consecutively, to relate the time of sputtering with the thickness of the removed material.…”

ToF-SIMS Depth Profiling of Metal, Metal Oxide, and Alloy Multilayers in Atmospheres of H2, C2H2, CO, and O2

“…One commonly applied approach is laser postionization of the neutral sputtered particles (laser-SNMS). 52 − 54 Since the particles are ionized in the plume, there is no matrix around them to affect the ionization. 53 Laser-SNMS can be used in depth profiling, 55 thereby improving the ionization yield.…”