SEM-EDX
Definition
Scanning electron microscopy with energy-dispersive X-ray spectroscopy. The electron beam excites characteristic X-rays from each element present in the target grain, giving a semi-quantitative elemental profile of individual particles. Used when optical properties alone are insufficient for identification.
- Particle size range
- Sub-10-micron spheres (GSR); nanometre-scale morphology on dust and minerals
- Key GSR elements
- Lead, barium, antimony (all three required for confirmation)
- Primary applications
- Gunshot residue confirmation, blast residue typing, printer and toner identification, mineral and dust classification
Common questions
What does SEM-EDX actually do?+
SEM-EDX combines scanning electron microscopy with energy-dispersive X-ray spectroscopy to image particles at high resolution and measure the elemental composition of individual particles at the same time. The electron beam excites characteristic X-rays from each element present, revealing both the shape and chemical makeup of tiny particles in a single analysis.
Why is SEM-EDX the gold standard for gunshot residue?+
It can identify the three signature elements of fired ammunition - lead, barium, and antimony - inside individual spherical particles smaller than 10 microns, all in one test. This combination of shape, size, and elemental signature is so characteristic that it confirms a shot was fired, meeting ASTM E1588 standards.
What kinds of samples can SEM-EDX analyze?+
It works on particles and grains across a wide range of scales: gunshot residue, blast-scene particles (including explosive initiator residues), printer toner and ink pigments, dust, minerals, and photocopier toner. It requires no sample dissolution, so individual particles keep their identity throughout analysis.
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Explained in these topics
- Dust and Airborne Mineral ParticlesScanning electron microscopy with energy-dispersive X-ray spectroscopy; provides nanometre-scale morphological images and elemental composition of individual p...
- Gunshot Residue (GSR) Analysis: Detection MethodsScanning electron microscopy with energy-dispersive X-ray spectroscopy. The gold-standard GSR confirmation, identifying single sub-10-micron spherical particle...
- Laboratory Explosives Analysis: LC-MS, GC-MS, IC, XRF and SEM-EDXScanning electron microscopy with energy-dispersive X-ray spectroscopy. Combines submicron-resolution imaging with elemental mapping at each point, used in pos...
- Optical Microscopy and Mineral IdentificationScanning electron microscopy with energy-dispersive X-ray spectroscopy. The electron beam excites characteristic X-rays from each element present in the target...
- Photocopier and Fax Examination, and Toner AnalysisScanning electron microscopy with energy-dispersive X-ray spectroscopy; used in toner analysis to characterise particle morphology, size distribution, and elem...
- Post-Blast Residue Sampling and the IMS, GC-ECD, LC-MS/MS WorkflowScanning electron microscopy with energy-dispersive X-ray analysis. Applied to residue particles from blast scenes to identify elemental composition at the sin...
- Printer Identification: Inkjet, Laser, Dot-Matrix, Yellow-DotScanning electron microscopy with energy-dispersive X-ray spectroscopy; used in printer forensics to characterise toner and ink pigment elemental composition,...