https://doi.org/10.1351/goldbook.ST07479

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

**Note:**

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.