Capability of aTES microcalorimeter SEM-EDS system for forensic analysis of automotive paint and gunshot residue

The analytical performance of a scanning electron microscopy-energy dispersive spectroscopy (SEM–EDS) system equipped with a transition edge sensor (TES) microcalorimeter (µ-cal) in forensic analysis is examined. The TES microcalorimeter shows much better energy resolution than the conventional solid-state detector (SSD). We solved some identification problems caused by peak overlaps when forensic samples were analyzed by a conventional SEM-EDS system based on SSD. The microcalorimeter ED spectrum can reveal the coexistence of Ba and S in a paint layer of an automotive white paint fragment containing TiO2 as pigment and this may indicate the existence of BaSO4. The coexistence of K, Mg, Al, Si and Ti in the surface layer suggests the use of titanium dioxide (TiO2)-coated mica as a pearlescent pigment in paint. GSR particles are successfully discriminated by detecting Ba, Sb, Pb and S. An elemental mapping function of the TES microcalorimeter system was introduced for the first time and revealed the accumulation of Pb- and Sb-rich particles in GSR. These results suggest that the microcalorimeter SEM–EDS system offers analysis with both high-energy resolution and high-spatial resolution at low-excitation voltages. These advantages are fully utilized as powerful analytical tools in forensic laboratories. Copyright © 2009 John Wiley & Sons, Ltd.