DrDu said:The electric fields of the optical wave polarize the electron clouds. The moving polarization of the electron clouds in turn leads to electrical fields which are partially emitted. However, the electric fields are not always emitted at the same point where the polarization and currents have been induced. If the resultant fields are furthermore rotated with respect to the incoming wave due to the low symmetry of the molecule, the polarization axis of the resultant field will be rotated.
Electric fields exert forces on the electrons and oppositely on the nuclei. Hence the centers of charge will separate and you will get a polarisation varying with the frequency of the incoming light. However, if the molecule isn't symmetrical, the polarisation will not be strictly along the direction of the incoming field. Hence the field of the fluctuating dipoles will be tilted as compared to the incoming field, i.e. the plane of polarisation gets rotated.Vivek des said:How does the electron cloud gets polarized?
Optical activity is a phenomenon in which chiral molecules, also known as molecules with a non-superimposable mirror image, rotate the plane of polarized light passing through them.
Chiral molecules rotate light because they have an uneven distribution of electrons, which causes them to interact differently with polarized light. This interaction results in the rotation of the plane of polarized light.
The relationship between a molecule's chirality and its ability to rotate light is that only chiral molecules have the ability to rotate light. Molecules with no chirality, such as symmetrical molecules, will not rotate light.
Optical activity is measured using a polarimeter, which is an instrument that measures the rotation of polarized light passing through a sample of a chiral molecule. The amount of rotation is then used to determine the concentration and purity of the sample.
Optical activity has many real-life applications, including in pharmaceuticals, where it is used to determine the purity and concentration of chiral drugs. It is also used in the food industry to detect additives and in organic chemistry to determine the structure of chiral molecules.