https://doi.org/10.1351/goldbook.AT07312

Number of photons of a particular wavelength per time interval (spectral photon flux, number basis, \(q_{\text{p},\lambda }\), or spectral photon flux, amount basis, \(q_{n,\text{p},\lambda }\)) absorbed by a system per volume, \(V\). On number basis, SI unit is \(\text{s}^{-1}\ \text{m}^{-4}\) common unit is \(\text{s}^{-1}\ \text{cm}^{-3}\ \text{nm}^{-1}\) On amount basis, SI unit is \(\text{mol s}^{-1}\ \text{m}^{-4}\) common unit is \(\text{einstein}\ \text{s}^{-1}\ \text{cm}^{-3}\ \text{nm}^{-1}\).**Notes: **

*Source: *

PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 297 (https://doi.org/10.1351/pac200779030293)

- Mathematical expression: \(\frac{q_{p,\lambda }^{0}[1 - 10^{-A(\lambda )} ]}{V}\) on number basis, \(\frac{q_{n,p,\lambda }^{0}[ 1 - 10^{-A(\lambda )} ]}{V}\) on amount basis, where \(A(λ)\) is the @A00028@ at @W06659@ \(λ\) and superscript \(0\) (zero) indicates incident photons.
- Absorbed spectral photon flux density (number basis or amount basis) should be used in the denominator when calculating a differential @Q04991@ and using in the numerator the rate of change of the number concentration, \(\frac{dC}{dt}\) or the rate of change of the @A00295@, \(\frac{dc}{dt}\), respectively.

PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 297 (https://doi.org/10.1351/pac200779030293)