Frequency in
vibrational spectroscopy that is characteristic of a particular chemical functional group.
Note: The frequency is usually given as a
wavenumber.
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 748 (https://doi.org/10.1515/pac-2019-0203)