Plain polarized light , optical

Biot made the remarkable observation that, when a beam of plain -polarized light passes through a solution of certain organic molecules such as sugar or camphor, the plane of polarization is rotated. Not all organic substances exhibit this property, but those that do are said to be optically at tive. 

The most common form of optical activity was first measured at a constant wavelength by the angle of rotation of linearly polarized light. More recently the measurements have been extended to the entire range of visible and attainable ultraviolet regions where electronic transitions are observed, giving rise to the ORD technique (Optical Rotatory Dispersion). The Cotton effects appear in the region of optically active absorption bands outside of these bands the plain curve spectrum is also dependent on all the electronic transitions of the chromophores. 

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