observed interface width

synonym: depth resolution
https://doi.org/10.1351/goldbook.09443

In secondary-ion mass spectrometry, Auger electron spectroscopy, and X-ray photoelectron spectroscopy, distance over which a change in signal intensity from 16 % to 84 %, or from 84 % to 16 %, is measured at the junction of two dissimilar matrices, the thicknesses of which are more than six times that distance

Note: The change in signal intensity should be quoted with the observed interface width.
Source:
PAC, 2020, 92, 1781. (Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)) on page 1808 [Terms] [Paper]