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Chemical discrimination of multilayered paint cross sections for potential forensic applications using time‐of‐flight secondary ion mass spectrometry
Author(s) -
Muramoto Shin,
Gillen Greg,
Windsor Eric S.
Publication year - 2018
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/sia.6509
Subject(s) - secondary ion mass spectrometry , mass spectrometry , sputtering , analytical chemistry (journal) , chemistry , ion , time of flight , ion beam , time of flight mass spectrometry , materials science , chromatography , ionization , thin film , nanotechnology , organic chemistry
Time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS) equipped with a bismuth imaging source and an argon gas cluster ion beam (GCIB) was used to image polished cross‐sections of four automotive multilayer paint samples. Secondary ion mass spectrometry chemical imaging of the individual layers was possible after a GCIB sputter ion dose of (7 × 10 15 ) ions/cm 2 was applied for the removal of polishing residue, at which point the chemical composition of the individual clear coats could be distinguished using principal components analysis. For the differentiation of the four clear coat chemistries, only four secondary ion peaks were necessary; C 2 H 5 O + ( m/z 45.04), C 9 H 9 NO 2 + ( m/z 163.09), and C 10 H 11 NO 2 + ( m/z 177.10) that appeared to be fragments of the carbamate‐based clear coat, and C 7 H 11 + ( m/z 95.09) that was strongly associated with the polyurethane‐based clear coat. Clear identification of the four paint samples based on this short peak list highlights the strength of the SIMS technique as a potential forensic approach to discriminate automotive paints and suggests that many more variables could be included in the multivariate and statistical analysis to differentiate a wider range of clear coat chemistries.