Observables in Circular Dichroism Spectroscopy

As discussed previously, the different absorption exhibited by an optically active sample for the two circularly polarized components of a linearly polarized wave confers an elliptical polarization to the emerging radiation. The extent of such a polarization is expressed by means of the elhpticity 9 (in degrees or millidegrees)  

The quantity measured experimentally in CD spectroscopy is the difference between the absorbance of left- (Al) and right-handed (Ar) light at a given wavelength k 

For any wavelength, the elliptieity is related to the absorbance difference AA by the following equation  

In the case of an enantiomerieally pure species dissolved in solution, the Lambert-Beer law can be written as 

Occasionally, in particular for the biological area, circular dichroism spectra report the molar elliptieity [0], expressed in degrees L moP cm , in the place of As  

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