Distance travelled by a wave of
electromagnetic radiation in one cycle in a non-absorbing medium of real refractive index
\(n\).
\(\lambda = \lambda_{0}/n\).
Notes: - In spectroscopy, the unqualified term 'wavelength' frequently means the vacuum wavelength, and symbol \(\lambda\) frequently means \(\lambda_{0}\).
- SI unit: \(\pu{m}\). Common unit: \(\pu{nm}\) or \(\pu{\upmu\!m}\).
Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 678 (https://doi.org/10.1515/pac-2019-0203)