Application of Infrared and Raman Spectroscopy in Paint Trace Examination

Abstract

Raman spectroscopy has proved to be a promising technique in forensic examinations, where optical microscopy, micro-infrared spectroscopy, and microspectrophotometry in the visible and UV range are used for identification and differentiation between paint traces. Often no organic pigments are detected using Fourier transform infrared spectroscopy, because their content in a trace is usually undetectable. Application of a micro-Raman spectrometer equipped with several excitation lasers helps forensic experts in paint analysis enabling identification of main pigments. Three cases concerning comparative examination of car paint are discussed in detail. The comparison of Raman spectra of paint chips found on clothing of a victim or smears found on body of a damaged car to these of paint chips originated from the suspected car enabled us to identify the car involved in the accident. When no comparative material is available, the method can be useful in establishing the color and make of the car.