title: Reducing the Matrix Effect in Organic Cluster SIMS Using Dynamic Reactive Ionization.
abstract: Dynamic reactive ionization (DRI) utilizes a reactive molecule, HCl, which is doped into an Ar cluster projectile and activated to produce protons at the bombardment site on the cold sample surface with the presence of water. The methodology has been shown to enhance the ionization of protonated molecular ions and to reduce salt suppression in complex biomatrices. In this study, we further examine the possibility of obtaining improved quantitation with DRI during depth profiling of thin films. Using a trehalose film as a model system, we are able to define optimal DRI conditions for depth profiling. Next, the strategy is applied to a multilayer system consisting of the polymer antioxidants Irganox 1098 and 1010. These binary mixtures have demonstrated large matrix effects, making quantitative SIMS measurement not feasible. Systematic comparisons of depth profiling of this multilayer film between directly using GCIB, and under DRI conditions, show that the latter enhances protonated ions for both components by 4- to ~15-fold, resulting in uniform depth profiling in positive ion mode and almost no matrix effect in negative ion mode. The methodology offers a new strategy to tackle the matrix effect and should lead to improved quantitative measurement using SIMS. Graphical Abstract ᅟ.
authors.affiliation: Chemistry Department, The Pennsylvania State University, University Park, PA, 16802, USA. hut3@psu.edu.
authors.forename: Hua
authors.identifier: 0000-0002-3598-0219
authors.initials: H
authors.lastname: Tian
authors.affiliation: Fakultät für Physik, Universität Duisburg - Essen, 47048, Duisburg, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wucher
authors.affiliation: Chemistry Department, The Pennsylvania State University, University Park, PA, 16802, USA.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Winograd
mesh_terms: D007477:Ions; D011108:Polymers; D011522:Protons; D018629:Spectrometry, Mass, Secondary Ion; D014199:Trehalose
chemical_list: D007477:Ions; D011108:Polymers; D011522:Protons; D014199:Trehalose
keywords: Ar gas cluster ion beam; Depth profiling; Dynamic reactive ionization; Irganox; Matrix effect; Secondary ion mass spectrometry