spectral (photon) effectiveness 

https://doi.org/10.1351/goldbook.S05814
The reciprocal of the photon fluence rate, Ep0, at wavelength λ, causing identical photoresponse, Δy, per unit time (ΔyΔt). The effectiveness spectrum is directly proportional to the conversion spectrum of the sensory pigment, if spectral attenuance is negligible.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2275 [Terms] [Paper]
Citation: 'spectral (photon) effectiveness' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.S05814 RIS BibTex EndNote
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Last revised: February 24, 2014