full width at half maximum symbols: W, Γ

Synonym: full width at half height
Initialisms: FWHH, FWHM
https://doi.org/10.1351/goldbook.08251
Interval between the two points across a section of a spectrum where the ordinate is equal to half the maximum ordinate of the section.
Notes:
  1. W is a measure of line or band width.
  2. FWHM has units of wavelength, wavenumber, frequency, or energy.
  3. For infrared absorption spectra, the FWHM must be measured from a spectrum that is plotted linear in absorbance.
  4. In Raman spectra, the FWHM can be measured directly from the spectrum of scattered light intensity unless the instrument response function varies significantly across the band.
  5. Inclusion of "full" distinguishes FWHM from half-width at half maximum.
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 660 [Terms] [Paper]
Citation: 'full width at half maximum' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08251 RIS BibTex EndNote
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