## spectral irradiance, $$E_{\lambda}$$

https://doi.org/10.1351/goldbook.S05817
Irradiance, $$E$$, at wavelength $$\lambda$$ per unit wavelength interval. The SI unit is $$\text{W m}^{-3}$$, but a commonly used unit is $$\text{W m}^{-2}\ \text{nm}^{-1}$$.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2275 [Terms] [Paper]