Spectroscopic investigation of magnetic dipole allowed transitions through the magnetic transition moment

An experimental technique for detecting magnetic dipole allowed transitions by their dispersion-induced circular dichroism (DICD) is discussed. The DICD spectra of three nitrogen heterocycles (pyridine, pyrazine and tetraphenylporphyrin) are shown to be dominated by the n — π* transitions, as distinct from the normal absorption spectra which are dominated by the electric dipole allowed π — π* bands.