Knowledge Bank

Semiquantitatine theories of both type A and type B magnetic vibrational circular dichroism (MVCD) have been applied to the spectra observed by Devine and $Keiderling1,2$ The distinctive part of the theory is the detailed perturbation analysis of the part of the electronic momentum that is caused by nuclear motion. The treatment required going beyond the Born-Oppenneimer approximation. The theory accounts in a simple way for the sign and approximate magnitude of the dichroism in the fundamental vibrations of ammonia, methyl halides, and 1,3,5 tri-substituted benzenes.