Haemoglobin Spin State
Definition
The electronic configuration of iron in the haem group, either high-spin or low-spin. Oxyhaemoglobin and methaemoglobin differ in spin state, and Raman spectroscopy can detect this via marker bands in the porphyrin ring vibration region.
- Property measured
- Electronic configuration of the haem iron
- States
- High spin, low spin
- Contrast pair
- Oxyhaemoglobin vs methaemoglobin
- Detection method
- Raman spectroscopy, porphyrin ring marker bands
Common questions
How does spin state differ from the haemoglobin species itself?+
Species describes the chemical form of haemoglobin, while spin state describes the electron arrangement of the iron atom within that form, so two species can be compared by whether their iron sits in a high spin or low spin configuration.
Why use Raman spectroscopy rather than colour observation to assess spin state?+
The porphyrin ring vibration bands shift measurably with spin state, giving a quantitative, reproducible reading that visual colour comparison cannot provide, especially on aged or discoloured stains.
What is the practical value of spin-state analysis in casework?+
It adds a second, independent line of chemical evidence to species-based ageing, useful when a stain's colour has degraded so much that visible reflectance alone becomes ambiguous.
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