Differentiation of spectra as a means of resolving spin-forbidden bands: iron(III) complexes

Abstract

Calculated second and fourth differentials of iron(III) spectra in molten salts (an extreme case, where temperature-broadened spin-forbidden transitions barely show up on an intense charge-transfer band edge) have resolved out expected transitions, plus some more which are tantatively assigned; this approach, which requires no prior knowledge of the correct number of bands present or their mathematical shape, is thus capable of resolving and subseuently assigning ligand-field spectra, but cannot be directly performed on modern spectrophoto-meters without due care being taken.