https://doi.org/10.1351/goldbook.P04636
Number of photons (quanta of radiation, \(N_{\text{p}}\)) per time interval. SI unit is \(\text{s}^{-1}\).
Notes:
- Mathematical definition: \(q_{\text{p}} = \text{d}N_{\text{p}}/\text{d}t\). If the number of photons is constant over the time interval, \(q_{\text{p}} = N_{\text{p}}/t\).
- This quantity can be used on a @C01019@ basis by dividing the photon flux, number basis, \(q_{\text{p}}\), by the @A00543@, the symbol then being \(q_{n\text{,p}}\), the name 'photon flux, amount basis', SI unit is \(\text{mol s}^{-1}\); common unit is \(\text{einstein s}^{-1}\).
- Although the symbol recommended by CEI is \(\mathit{\Phi} _{\text{p}}\), the symbol \(q_{\text{p}}\) is preferred since \(\mathit{\Phi}\) is reserved for @Q04991@.