https://doi.org/10.1351/goldbook.P04634
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 (\(\text{quanta m}^{-2}\)). SI unit is \(\text{m}^{-2}\).
Notes:
- Mathematical definition: \(H_{\text{p,o}} = F_{\text{p,o}} = \text{d}N_{\text{p}}/\text{d}S = \int_{t}E_{\text{p,o}}\text{d}t\) with \(E_{\text{p,o}}\) the @P04635@, integrated over the duration of the @I03255@, \(t\). If \(E_{\text{p,o}}\) is constant over the time interval, \(H_{\text{p,o}} = F_{\text{p,o}} = E_{\text{p,o}}\,t\).
- This quantity can be used on a @C01019@ basis by dividing \(H_{\text{p,o}}\) by the @A00543@, the symbol then being \(H_{n\text{,p,o}}\), the name 'photon fluence, amount basis', SI unit is \(\text{mol m}^{-2}\); common unit is \(\text{einstein m}^{-2}\).