ATR-FTIR (Attenuated Total Reflectance FTIR)
Definition
An FTIR sampling mode in which infrared light undergoes total internal reflection in a crystal pressed against the sample surface, probing only the outer few micrometres; effectively non-destructive for ink surface analysis.
- Full name
- Attenuated total reflectance FTIR
- Mechanism
- Total internal reflection of IR light in a pressed crystal
- Sampling depth
- Outer few micrometres of the sample surface
- Sample handling
- Effectively non-destructive
- Forensic use
- Ink and surface material analysis on documents
Common questions
Why is ATR-FTIR preferred over transmission FTIR for ink on a document?+
ATR requires only surface contact with a crystal rather than transmitting light through a thin sample or extract, so it avoids cutting or dissolving the questioned document. That makes it suitable when the original paper must be preserved as evidence.
What is a limitation of ATR-FTIR for ink analysis?+
Because it only samples a shallow surface layer, it can miss compositional differences deeper in the ink layer or paper substrate, and firm, even contact between the crystal and an uneven or textured surface is needed for a reliable spectrum.
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