spectral irradiance, Eλ

https://doi.org/10.1351/goldbook.S05817
Irradiance
, E, at
wavelength
λ per unit
wavelength
interval. The SI unit is W m3, but a commonly used unit is W m2 nm1.
Source:
PAC, 1996, 68, 2223. (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2275 [Terms] [Paper]
See also:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2198 [Terms] [Paper]