Device used to eliminate photons of energies other than those in a narrow energy or wavelength band.
Note: For X-ray photoelectron spectroscopy using \(\ce{Al}\) X-rays, the monochromator is usually aligned close to the \(\ce{Al}\) \(\ce{K}\upalpha\!_{1}\) energy.
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1819 (https://doi.org/10.1515/pac-2019-0404)