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Chemical Discrimination of Multilayered Paint Cross Sections for Potential Forensic Applications using Time-of-Flight Secondary Ion Mass Spectrometry

Published

Author(s)

Shinichiro N. Muramoto, J Greg Gillen, Eric S. Windsor

Abstract

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. SIMS chemical imaging of the individual layers was possible after a GCIB sputter ion dose of 7 × 1015 ions/cm2 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 (PCA). For the differentiation of the four clear coat chemistries, only four secondary ion peaks were necessary; C2H5O+ (m/z 45.04), C9H9NO2+ (m/z 163.09), and C10H11NO2+ (m/z 177.10) that appeared to be fragments of the carbamate-based clear coat, and C7H11+ (m/z 95.09) which 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.
Citation
Surface and Interface Analysis

Keywords

tof-sims, gas cluster ion beam, paint multilayer, forensic science, chemometrics

Citation

Muramoto, S. , Gillen, J. and Windsor, E. (2018), Chemical Discrimination of Multilayered Paint Cross Sections for Potential Forensic Applications using Time-of-Flight Secondary Ion Mass Spectrometry, Surface and Interface Analysis (Accessed February 1, 2023)
Created June 15, 2018, Updated October 13, 2022