Soret Band
Definition
The intense porphyrin absorption band of haemoglobin at 415 nm; the spectral basis for bloodstain contrast enhancement.
- Wavelength
- 415 nm
- Origin
- Porphyrin absorption of haemoglobin
- Application
- Spectral basis for bloodstain contrast enhancement
- Field
- Forensic light source and imaging technique
Common questions
How is the Soret band exploited to enhance bloodstains on difficult surfaces?+
Illuminating or imaging around 415 nm exploits haemoglobin's strong absorption at that wavelength, so blood appears markedly darker against backgrounds that reflect that light, which can reveal stains on patterned, dark or partially cleaned surfaces that are hard to see under normal white light.
Does the Soret band identify blood specifically, or could other substances cause similar contrast?+
Strong absorption near 415 nm is characteristic of haemoglobin but is not exclusive to it, so contrast enhancement at this wavelength is a presumptive visualisation aid rather than a confirmatory test, and any suspected bloodstain still requires a chemical or serological confirmatory test.
Related terms
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- Mid-Infrared (Mid-IR)
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- Photon
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- Planck-Einstein Equation
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