\(-\log_{10}\) of the
spectrum obtained in
attenuated total reflection spectroscopy.
Note:
The term is used to avoid the confusing, but common and incorrect, practice of calling it the absorbance spectrum.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 759 (https://doi.org/10.1515/pac-2019-0203)