In ion-scattering spectrometry, increase in the spectrometer detection system response above the background signal, which can be attributed to the
binary elastic scattering of an incident ion by a surface atom of a particular mass.
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1832 (https://doi.org/10.1515/pac-2019-0404)