## spectral sensitivity, $$S(\lambda)$$

https://doi.org/10.1351/goldbook.ST07395
Referred to @[email protected] based on spectrophotometric measurements, $$S_{\text{ac}}\left(\lambda \right)=\varPhi \left(\lambda \right)\ \varepsilon\left(\lambda _{\text{obs}}\right)=\text{sensitivity or actinometric factor}$$. $$\varPhi \left(\lambda \right)$$ is the @[email protected] of the @[email protected] at the excitation @[email protected] and $$\lambda _{\text{obs}}$$ is the observation @[email protected], 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]