Photo via M Glasgow/Flickr
In what might be described as the most film-noir study of all time, forensic scientists have figured out how to identify the brand of lipstick found smeared at a crime scene, without removing the wine glass, shirt collar or cigarette butt from the evidence bag.
When hardboiled detectives are following leads on foggy nights, it’s important to not contaminate the evidence, as there’s already been enough lies, enough false accusations. Researchers at the University of Kent have figured out a way to use Raman spectroscopy, which measures how a chemical bonds scatter light, and can do so through a plastic bag. According to a little canary on the inside:
When a material - in this case lipstick - scatters light, most of the light is scattered at its original wavelength but a very small proportion is scattered at altered wavelengths due to changes in vibrational energy of the material’s molecules. This light is collected using a microscope to give a Raman spectrum, which gives a characteristic vibrational fingerprint which can be compared to spectra of lipsticks of various types and brands. Hence it is possible to determine identity of the lipstick involved.
Hence tracking down the femme fatales, wealthy dowagers and international jewel thieves in disguise just became that much easier. “For forensic purposes Raman spectroscopy also has the advantages that microscopic samples can be analyzed quickly and non-destructively,” said Michael Went, professor at the University of Kent school of physical sciences.
In spite of the fact that his name rhymes with his workplace, Went’s research interests include “the detection of drugs in fingerprints, detection of cosmetics as trace evidence, detection of GHB, recovery of fingerprints from metal surfaces, trace metal content of street drugs, contamination of drugs with gunshot residue and color determination using fibre (sic) optic visible spectroscopy."
Since it can identify the "fingerprint" of specific molecules, raman spectrometry has mostly been used in chemistry. It can be used to identify the composition of smoke rising from smokestacks and may someday be used to identify mineral composition of the surface of Mars.
Although researchers are working on it, using Raman spectrometry to identify skin cremes and or other make-up smears remain the stuff dreams are made of.