EDX / EDXRF
Definition
Energy-dispersive X-ray detector attached to an SEM. Identifies elements from characteristic X-rays emitted when the beam strikes the sample. Backbone of GSR analysis.
- Full name
- Energy-dispersive X-ray (fluorescence) detector
- Mounted on
- Scanning electron microscope
- Signal source
- Characteristic X-rays from beam-sample interaction
- Primary forensic use
- Gunshot residue analysis
Common questions
Why is SEM-EDX considered the backbone of gunshot residue analysis?+
It combines high-magnification imaging of characteristic spherical particle morphology with simultaneous elemental analysis, so an examiner can confirm both the shape and the lead, barium, antimony composition that together distinguish gunshot residue from look-alike particles.
Can EDX alone confirm a particle as gunshot residue without morphology?+
Elemental composition matching lead, barium, and antimony is treated as supportive rather than sufficient on its own, because the characteristic fused spherical morphology seen under SEM imaging is what rules out coincidental sources of similar elements.
Related terms
- Comparison Microscope
- Two compound microscope bodies connected by an optical bridge that presents one half of each body's image in a single split eyepiece...
- Depth of Field
- Axial thickness of the specimen that appears acceptably in focus at one time. High in stereoscopic microscopes, very low in oil-immersion compound...
- Fluorescence Microscope
- Uses UV or short-wavelength excitation to make fluorophores emit longer-wavelength light. Used for semen, saliva, fibres and ink discrimination.
- Numerical Aperture (NA)
- The product of the refractive index of the medium between objective and specimen and the sine of the half-angle of the maximum...
- Polarising Microscope
- Compound microscope fitted with a polariser below and an analyser above the stage. Used to study birefringent materials like fibres, minerals and...
- Resolution
- The ability of a mass analyser to distinguish two ions of nearly equal m/z, defined as m/Δm at a given peak. A...
- SEM
- Scanning electron microscope. Focused electron beam raster-scans the sample surface; resolution down to a few nanometres with great depth of field. Paired...
- Stereoscopic Microscope
- Two separate light paths producing a true 3D image at low magnification (typically 7x to 40x). Used for trace recovery, gross examination...
- TEM
- Transmission electron microscope. Electrons pass through an ultra-thin section; resolution below 1 nm. Rare in routine forensic casework, common in research.