chiroptiques

Chiroptiques is a term that describes optical phenomena or properties that are chiral. Chirality, in general, refers to a geometric property of an object that is non-superimposable on its mirror image, much like a left hand and a right hand. In the context of optics, this means that materials or systems exhibit different behaviors when interacting with left-handed and right-handed circularly polarized light.

When circularly polarized light, which has a helical wavefront, passes through a chiral medium, it can be rotated. This rotation is known as optical activity. If the medium rotates the plane of polarization of linearly polarized light to the right (clockwise), it is dextrorotatory. If it rotates to the left (counterclockwise), it is levorotatory. The magnitude of this rotation depends on the concentration of the chiral substance, the path length of the light through the substance, and the wavelength of the light.

Chiroptical spectroscopy techniques, such as circular dichroism (CD) and circular intensity differential scattering (CIDS), are used to study these chiral properties. Circular dichroism measures the differential absorption of left and right circularly polarized light by a chiral molecule. This technique is particularly valuable in determining the secondary and tertiary structures of biomolecules like proteins and DNA, as well as in identifying and characterizing chiral organic compounds. Circular intensity differential scattering, on the other hand, probes the scattering of circularly polarized light by chiral particles. Chiroptical effects are fundamental in understanding the interactions of light with chiral matter and have applications in chemistry, biology, and materials science.