IUPAC - wavenumber in vacuum (08302)

wavenumber in vacuum symbol: $\tilde{ν}$ , units: $m^{- 1}$ , ${cm}^{- 1}$

Synonym: vacuum wavenumber

https://doi.org/10.1351/goldbook.08302

Reciprocal of the vacuum wavelength of electromagnetic radiation.

\tilde{ν} = 1 / λ_{0}

Notes:

Wavenumber is related to the energy change, $Δ E$ , induced when the radiation is absorbed by $Δ E = h c_{0} \tilde{ν}$ , where $h$ is the Planck constant and $c_{0}$ the speed of the radiation.
Wavenumber should only be used when no confusion with frequency is possible.
The symbol $ν$ is often used instead of $\tilde{ν}$ ; this usage should be discouraged.
SI unit: $m^{- 1}$ . Common unit: ${cm}^{- 1}$ .

Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 678 [Terms] [Paper]

Citation: 'wavenumber in vacuum' 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.08302 RIS BibTex EndNote

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Version 3.0.1 (6776 Terms)

wavenumber in vacuum symbol: $\tilde{ν}$ , units: $m^{- 1}$ , ${cm}^{- 1}$

Alphabetical Index

Additional Indexes

Version 3.0.1 (6776 Terms)

wavenumber in vacuum symbol: ν~, units: m−1, cm−1

wavenumber in vacuum symbol: $\tilde{ν}$ , units: $m^{- 1}$ , ${cm}^{- 1}$