## derivative spectroscopy

https://doi.org/10.1351/goldbook.D01610
The first (second, ...) derivative @[email protected] of a molecule is defined as the first (second, ...) derivative, $$\frac{\text{d}A\left(\overset{˜}{\nu }\right)}{\text{d}\overset{˜}{\nu }}$$[$$\frac{\text{d}^{2}A\left(\overset{˜}{\nu }\right)}{\text{d}\overset{˜}{\nu }^{2}}$$, ... ] of the @[email protected] $$A$$ as a function of wavenumber, $$\overset{˜}{\nu }$$. Wavelengths may be used in place of wavenumbers but the shape of the derivative spectra will be slightly different. When derivative spectra are obtained at low temperature, they are called first (second, ...) derivative @[email protected] (specifying the solvent, temperature and solute concentration).
Source:
PAC, 1988, 60, 1449. (Nomenclature, symbols, units and their usage in spectrochemical analysis - VII. Molecular absorption spectroscopy, ultraviolet and visible (UV/VIS) (Recommendations 1988)) on page 1455 [Terms] [Paper]