1.
Please describe the differences between circular dichroism (CD) and optical rotation ([a] D ).
Describe the differences in how the spectra are measured, what information is recorded, and how
that information can be used in a lab scenario.
Solution
Optical rotation ([a]D):
The phenomena that [?] varies with wave length is named as optical rotatory dispesion.
Circular dichroism (CD):
If two circularly polarized components are dfferentially absorbed by the medium: this leads to
the emergent beam having an imbalance between the strengths of the two circularly polarized
beams, so that the emergent beam is not truly plane polarized but elliptcally polarized. We name
this phenomena is as circlar dichroism.
The currently available spectropolarimeters and circular dichrometers utilitie a single beam
optical system.
In the Cary 60 spectropolarimeter , however the folded optical beam is capable of making
difference ORD measurements by means of a specially designed cell holder.The difference ORD
technique can be a useful tool for measuring small changes in optical rotation of protein
solutions under various conditions, such as change in pH and temperature.