Vector in reciprocal space describing the direction of propagation of X-rays and equal in magnitude to
\(2\uppi/\lambda\), where
\(\lambda\) is the wavelength of the X-rays.
Note: In different fields of study, the wave vector is taken as \(2\uppi/\lambda\) or as \(1/\lambda\). In X-ray reflectometry the former is usually used.
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1849 (https://doi.org/10.1515/pac-2019-0404)