Application of Surface-Enhanced Raman Spectroscopy to Forensic Auto Paint Analysis

Hello everyone! Have you ever been in a situation where your car was involved in a hit and run accident? Usually when this happens a paint sample is left behind by the car that hit you. This paint sample can be used in forensic analysis to identify the car of the offender. My research over the summer will be in applying a new analytical method in order to solve this common crime amongst other crimes involving paint evidence.

Currently forensic paint analysis uses Raman spectroscopy to examine paint evidence, however, Raman spectroscopy has several limitations including sample size, the fluorescing nature of the chromophore in paint pigments, and low intensity spectra. The analytical method I will be studying uses Surface-enhanced Raman spectroscopy (SERS) to examine the chromophore. SERS combats the limitations of Raman spectroscopy by mixing metal nanoparticles with the paint sample. This allows SERS to analyze minuscule samples, quench fluorescence, and give high intensity, distinct spectra. The high intensity, distinct spectra, which are alike to a fingerprint for the chromophore,  will eventually be used as an identifier for the make, model, and year of a car. Car paint samples are unique from other paint samples in the fact that they have multiple layers to them. A paint sample from a car can have layers of top coat, paint additives, binders as well as the paint pigment. This poses several problems with SERS analysis since SERS is used to identify the chromophore. Over the summer I will be developing a method to strip car paint samples of their multiple layers to get down to the chromophore level. This will hopefully lead to reliable methodology which will be submitted for publication, as well as, a SERS spectra database of modern cars that will be used for forensic paint analysis. I look forward to updating you all on my quest to solve common crime!