Number of particles detected with a spectrometer divided by the number of such particles per solid angle and per interval of the dispersing parameter available for measurement as a function of the dispersing parameter.
See also: spectrometer transmission function
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1813 (https://doi.org/10.1515/pac-2019-0404)