Evans hole

https://doi.org/10.1351/goldbook.08597
Unexpected minimum or hole in a broad absorption band due to a gap being created in a broad distribution of states by Fermi resonance.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 745 [Terms] [Paper]