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Absorption spectrum


An absorption spectrum represents the absorption of a molecule as a function of wavelength.

Graph of an absorption spectrum. Abscissa = wavelength in nm, ordinate = absorbance A or transmittance T.

Y-axis

Y-axis = absorbance A or transmittance T

Aλ = log I0/I without unit
Tλ = 10-Aλ = I/I0

X-axis

On the X-axis = wavelength in nm

Click on each box to find out more

Chemical groups responsible for absorption are called chromophores.
For gases, absorption bands are thin, although for liquids they can be tens of nanometers wide.

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