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]