DISCLAIMER: This article is being kept online for historical purposes. Though accurate at last review, it is no longer being updated. The page may contain broken links or outdated information.
Origin of optical activity
Pagni, R. M. Department of Chemistry, University of Tennessee, Knoxville, Tennessee.
- Optical rotation
- Asymmetric synthesis in nature
- Related Primary Literature
- Additional Reading
In order to explain optical activity, it is helpful first to discuss linearly and circularly polarized light. Light can be thought of as a wave or a particle (wave-particle duality). In wave theory, light is an electromagnetic wave propagating with a velocity v (c = v in vacuum). The wave consists of an electric field E oscillating in a plane perpendicular to the direction of propagation, and a mutually perpendicular magnetic field H. Both are oscillating with a frequency ν, and the distance between successive maxima of E or H is the wavelength λ, such that λ = v/ν. If E oscillates in a specific plane relative to the propagation direction (plane of polarization), the light is said to be linearly polarized. If two mutually perpendicular linearly polarized electromagnetic waves are combined, having the same frequency and direction of propagation but with phases differing by one-quarter wavelength, the resultant E vector rotates about the propagation direction. If the direction of rotation is clockwise as viewed in the direction of the light source, the light is said to be right-circularly polarized (RCPL), and it is left-circularly polarized (LCPL) if the rotation is in the opposite direction. In particle theory, a quantum of light is called a photon, with energy equal to Planck's constant h times the frequency, or hν. Photons also have unit intrinsic angular momentum of + (equal to h/2π) along the direction of propagation (RCPL) or − against the direction of propagation (LCPL). Linearly polarized light is an equal mixture of these two photon beams.
The content above is only an excerpt.
for your institution. Subscribe
To learn more about subscribing to AccessScience, or to request a no-risk trial of this award-winning scientific reference for your institution, fill in your information and a member of our Sales Team will contact you as soon as possible.
to your librarian. Recommend
Let your librarian know about the award-winning gateway to the most trustworthy and accurate scientific information.
AccessScience provides the most accurate and trustworthy scientific information available.
Recognized as an award-winning gateway to scientific knowledge, AccessScience is an amazing online resource that contains high-quality reference material written specifically for students. Contributors include more than 9000 highly qualified scientists and 43 Nobel Prize winners.
MORE THAN 8700 articles covering all major scientific disciplines and encompassing the McGraw-Hill Encyclopedia of Science & Technology and McGraw-Hill Yearbook of Science & Technology
115,000-PLUS definitions from the McGraw-Hill Dictionary of Scientific and Technical Terms
3000 biographies of notable scientific figures
MORE THAN 19,000 downloadable images and animations illustrating key topics
ENGAGING VIDEOS highlighting the life and work of award-winning scientists
SUGGESTIONS FOR FURTHER STUDY and additional readings to guide students to deeper understanding and research
LINKS TO CITABLE LITERATURE help students expand their knowledge using primary sources of information