The spectral output quantity of a system such as a photomultiplier, diode array, photoimaging device, or biological unit divided by the spectral irradiance s λ = d y λ d E λ, simplified expression: s λ = Y λ E λ, where Y λ is the magnitude of the output signal for irradiation at wavelength λ and E λ is the spectral irradiance of the parallel and perpendicular incident beam at the same wavelength.
See also: responsivity (in detection of radiation)
Sources:
PAC, 1995, 67, 1745. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-XI. Detection of radiation (IUPAC Recommendations 1995)' on page 1749 (https://doi.org/10.1351/pac199567101745)
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2276 (https://doi.org/10.1351/pac199668122223)