spectral sensitivity, \(S_{\lambda}\)

https://doi.org/10.1351/goldbook.ST07395
Referred to @A00087@ based on spectrophotometric measurements, \(S_{\text{ac}}\left(\lambda \right)=\Phi \left(\lambda \right)\ ɛ\left(\lambda _{\text{obs}}\right)=\text{sensitivity or actinometric factor}\). \(\Phi \left(\lambda \right)\) is the @Q04991@ of the @A00087@ at the excitation @W06659@ and \(\lambda _{\text{obs}}\) is the observation @W06659@, which may be the same as or differ from the former.
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 426 [Terms] [Paper]