SEM-EDS
Definition
Scanning electron microscopy with energy-dispersive X-ray spectroscopy; provides elemental composition of each paint layer at 1-5 µm spatial resolution.
- Spatial resolution in paint analysis
- 1-5 micrometers per layer
- What it measures
- Microstructure plus elemental composition simultaneously
Common questions
What does SEM-EDS actually show you in forensic samples?+
SEM-EDS gives you two things at once: a detailed microscope image of the sample's surface structure, plus elemental composition data showing which elements are present. For paint layers, it can pinpoint the elemental composition at fine detail down to 1-5 micrometers. This lets you match paint fragments or analyze layered evidence like cement and building materials.
How is SEM-EDS different from just looking at a sample under a regular microscope?+
A regular microscope shows you what things look like. SEM-EDS tells you what they're made of. The scanning electron microscope gives much higher magnification and clearer detail of tiny structures, while the energy-dispersive X-ray spectroscopy component identifies each chemical element present. Together, they're more powerful than either technique alone.
Why is SEM-EDS useful for paint and building material evidence?+
Paint comes in layers, each with different chemical compositions. SEM-EDS can distinguish each layer and identify their elements, making it useful for linking paint chips or examining layered deposits. For cement and plaster, it reveals the mineral and elemental makeup, helping establish source and manufacturing details.
Related terms
- ASTM C150
- US standard specifying Portland-cement composition limits and performance requirements by type (I through V); referenced in forensic mineral-phase characterisation.
- ASTM E2937
- ASTM International standard guide for identification of paint binders by pyrolysis-GC-MS; specifies pyrolysis conditions, GC column, oven program, and diagnostic ion reporting.
- ATR (Attenuated Total Reflectance)
- An FTIR sampling mode in which the sample is pressed against a diamond or ZnSe crystal and the evanescent wave probes the...
- Backscattered Electron (BSE) Imaging
- An SEM imaging mode sensitive to atomic number and crystallographic texture; can reveal grain-boundary elongation patterns in the sub-surface cold-worked zone after...
- Calcium Sulphate Hemihydrate
- CaSO4 . 1/2 H2O; produced by heating gypsum, rehydrates to gypsum on setting; the basis of plaster of Paris and most interior...
- Clinker
- The nodular intermediate product of Portland-cement manufacture, consisting of C3S, C2S, C3A and C4AF mineral phases before grinding.
- ENFSI ENG-FG1
- The European Network of Forensic Science Institutes' guidelines for forensic geological evidence, published in 2018 by the Expert Working Group on Forensic...
- ENFSI EPG Protocol
- European Network of Forensic Science Institutes Expert Working Group on Paint protocol; the European standard for paint comparison examination sequence and reporting.
- Ettringite
- A calcium sulfoaluminate hydrate that forms early in cement hydration and can re-form later from delayed sulfate attack; its presence or alteration...
- FTIR (Fourier Transform Infrared Spectroscopy)
- A vibrational spectroscopy technique used in toner analysis to identify the polymer backbone and functional group composition of toner binder material; ATR...
- FTIR Microspectroscopy
- Fourier-transform infrared spectroscopy collected from a microscope-focused spot of 10-20 µm diameter; the primary technique for paint binder characterisation.
- IRUG Database
- Infrared and Raman Users Group spectral database; covers historic pigments, artists' materials, and museum-object coatings. Primary reference for art-investigation paint analysis.
Explained in these topics
- Cement, Plaster and Building-Material EvidenceScanning electron microscopy plus energy-dispersive X-ray spectroscopy; provides microstructure imaging and elemental composition simultaneously.
- Paint Layer Examination: Cross-Section, FTIR and Py-GC-MSScanning electron microscopy with energy-dispersive X-ray spectroscopy; provides elemental composition of each paint layer at 1-5 µm spatial resolution.