Analysis of Pieces of Evidence

IR and Raman spectroscopy and microscopy are widely used analytical methods in forensic science to gather chemical information about pieces of evidence.

FT-IR spectroscopy combined with the ATR technique allows to measure spectra of almost all kinds of solid and liquid samples without any sample preparation. Raman even facilitates contact-free measurements of material enclosed in their packaging. The identification of any sample is accomplished by automatic search of the measured sample spectrum in spectra libraries.

The identity of samples relevant in forensics like drugs and toxics can be determined within some seconds analysis time using the very compact and easy-to-use FT-IR spectrometer ALPHA II. For the analysis a few milligrams substance are required.

Trace evidence like particles and fibers might not allow a conventional IR-spectroscopic measurement. To obtain spectra of samples with dimensions down to a few micrometers the fully automated IR microscope LUMOS is a very suitable instrument. IR microscopy is also the method of choice to perform laterally resolved measurements of heterogeneous samples.

As an example characterizing the individual layers of a paint chip found at a crime scene or accident allows determining the model of the involved car. Also the differentiation and identification of inks and printer toners by their chemical fingerprints is a typical application when investigating counterfeit documents or blackmailing letters.

The Raman microscope SENTERRA II can be utilized for the contactless analysis of various samples with a spatial resolution of up to 1µm. Furthermore its confocal design allows the direct measurement of material packed inside glass vials, plastic containers or bags.