spectral radiant energy density

symbols: $\rho_{\tilde{\nu}}(\tilde{\nu})$, $\rho_{\lambda}(\lambda)$, unit: $\pu{J m-2}$

https://doi.org/10.1351/goldbook.08287

Radiant energy density in unit wavenumber (wavelength) interval at wavenumber $\tilde{\nu}$ (wavelength $\lambda$).

Note:
SI unit: $\pu{J m-2}$.

Source:
PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 674 (https://doi.org/10.1515/pac-2019-0203)