Number of ions of a particular species sputtered from a sample divided by number of particles of that species sputtered from that sample.
See also: fractional sputtering yield, partial sputtering yield, total ion yield
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1839 (https://doi.org/10.1515/pac-2019-0404)