spectral fluence rate, \(E_{\lambda,\text{o}}\)

Derivative of @[email protected], \(E_{\text{o}}\), with respect to @[email protected], \(\lambda\). SI unit is \(\text{W m}^{-3}\); common unit is \(\text{W m}^{-2}\ \text{nm}^{-1}\).
All spectral terms may also be defined as derivatives with respect to frequency, \(\nu\), or wavenumber, \(\tilde{\nu}\), and are referred to, when necessary, as in terms of @[email protected], or frequency or wavenumber, respectively.
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 423 [Terms] [Paper]