Category Archives: signals

Circular polarization of EM wave or PHOTONIC energy yields a DOUBLE HELIX radiation pattern!

Since this is an electromagnetic wave each electric field vector has a corresponding, but not illustrated, magnetic field vector that is at a right angle to the electric field vector and proportional in magnitude to it.

As a result, the magnetic field vectors would trace out a second helix if displayed

Circular dichroism (CD) is the differential absorption of left- and right-handed circularly polarized light. Circular dichroism is the basis of a form of spectroscopy that can be used to determine the optical isomerism and secondary structure of molecules.

In general, this phenomenon will be exhibited in absorption bands of any optically active molecule.

As a consequence, circular dichroism is exhibited by most biological molecules, because of the dextrorotary (e.g. some sugars) and levorotary (e.g. some amino acids) molecules they contain.

Noteworthy as well is that a secondary structure will also impart a distinct CD to its respective molecules.

Therefore, the alpha helix, beta sheet and random coil regions of proteins and the double helix of nucleic acids have CD spectral signatures representative of their structures.

Also, under the right conditions, even non-chiral molecules will exhibit magnetic circular dichroism, that is, circular dichroism induced by a magnetic field.

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