Effective Transition Probability for the Faraday Effect of Lanthanide(III) Ion Solutions

The Faraday effects of 14 lanthanide(III) ion solutions were systematically analyzed on the basis of the Faraday C term. The effective transition probability, K, which measures the magneto-optical contribution of the 4f n → 4f n−15d transition to the molar Verdet constant, was determined. Linear correlations between K and the square root of the molar magnetic susceptibility of the lanthanide(III) ions, χm 1/2, were obtained. From the observed new regularity, K for promethium(III) was estimated.