The principles of derivative spectrophotometry have been known for many years, and a variety of instrumentation for producing the first and higher differentials of absorption spectra has been described. However, despite the advantages of the techniques for intensifying minor changes in spectra, the separation of overlapping bands, or for band sharpening, derivative traces have not been used to a significant extent in infrared spectroscopy.
M. J. D. Low and H. Mark, "Derivative Traces in Infrared Fourier Transform Spectroscopy," Appl. Spectrosc. 24, 129-130 (1970)