Amount of photons (quanta of radiation) incident on a small sphere from all directions
, divided by the cross-sectional area of that sphere and integrated over time. Photons per surface area (quanta m-2). SI unit is m-2.
- Mathematical definition: Hp,o = Fp,o = dNp/dS = ∫(t) Ep,o.dt with Ep,o the @P04635@, integrated over the duration of the @I03255@, t. If Ep,o is constant over the time interval, Hp,o = Fp,o = Ep,o.t.
- This quantity can be used on a @C01019@ basis by dividing Hp,o by the @A00543@, the symbol then being Hn,p,o, the name 'photon fluence, amount basis', SI unit is mol m-2; common unit is einstein m-2.
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 395 (https://doi.org/10.1351/pac200779030293)