photon flow, Φ p

https://dx.doi.org/10.1351/goldbook.P04633
The number of photons (quanta, N) per unit time. (d N d t, simplified expression: Φ p = N t when the number of photons is constant over the time considered). The SI unit is s −1. Alternatively, the term can be used with the amount of photons (mol or its equivalent einstein), the SI unit then being mol s −1.
See also: radiant power
Source:
PAC, 1996, 68, 2223 (Glossary of terms used in photochemistry (IUPAC Recommendations 1996)) on page 2263