https://doi.org/10.1351/goldbook.08301
Reciprocal of wavelength of electromagnetic radiation. \(\sigma = 1/\lambda\).
Notes:
- In spectroscopy, the unqualified term 'wavenumber' (sometimes referred to as "reciprocal centimetre" \(\pu{cm-1}\)) often means vacuum wavenumber, and symbol \(\sigma\) often means \(\tilde{\nu}\).
- SI unit: \(\pu{m-1}\). Common unit: \(\pu{cm-1}\).