escape depth (for surface analysis techniques)

https://doi.org/10.1351/goldbook.E02214
The distance into the sample measured from the physical surface from which all but a fraction \(\frac{1}{e}\) of the particles or radiation detected have originated.
Source:
PAC, 1979, 51, 2243. (General aspects of trace analytical methods—IV. Recommendations for nomenclature, standard procedures and reporting of experimental data for surface analysis techniques) on page 2247 [Terms] [Paper]