Standard spinels of the type formed during the oxidation of stainless steel surfaces have been analyzed by infrared techniques. Comparison of the spectra for each series of spinels shows that it is possible to identify the stoichiometry and structure of the spinel from its infrared spectrum.
Geoffrey C. Allen and Michael Paul, "Chemical Characterization of Transition Metal Spinel-Type Oxides by Infrared Spectroscopy," Appl. Spectrosc. 49, 451-458 (1995)