Magnetic Circular Dichroism
Magnetic circular dichroism (MCD) is the differential absorption of left and right circularly polarized light induced by a longitudinal magnetic field between different electronic states.
Similar to CD with respect to using the PEM.
A SIMPLE EXAMPLE FOR MEASURING THE ZEEMAN EFFECT
Electronic transition for an atom: 1S -> 1P
(one of the possibilities from s2 -> sp without spin-orbit coupling)
The three states of 1P will be split in the presence of a longitudinal magnetic field as shown above. The transition select rules govern that left and right circularly polarized light be absorbed at different energies. The resulting MCD spectrum is a derivative-like band whose amplitude is proportional to the Zeeman splitting.
The Zeeman splitting can be measured from MCD without resolving the hyperfine peaks. In the above figures, the Zeeman splitting is greatly exaggerated to illustrate the physical content. In reality, the MCD signal for diamagnetic species is generally on the order of 10-3 to 10-6. Furthermore, MCD can be observed in the IR region for vibrational transitions where it is called MVCD.
In physics, chemistry and biochemistry; hyperfine structures of atoms and molecules; analytical applications in biochemistry.
P. J. Stephens, Adv. Chem. Phys. 35, 197 (1976).
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