resonance effect magnitude

in Mössbauer spectrometry
https://doi.org/10.1351/goldbook.R05331
Ratio of the difference in the transmitted or scattered intensity at resonance maximum and off-resonance, relative to the intensity off-resonance.
Source:
PAC, 1976, 45, 211. (Nomenclature and Conventions for Reporting Mössbauer Spectroscopic Data) on page 214 [Terms] [Paper]