photon fluence, H p , o,F p , o
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.
  1. Mathematical definition: H p , o = F p , o = d N p / d S = ∫ t E p , o ⁢ d t with E p , o the photon fluence rate, integrated over the duration of the irradiation, t. If E p , o is constant over the time interval, H p , o = F p , o = E p , o t
  2. This quantity can be used on a chemical amount basis by dividing H p , o by the Avogadro constant, the symbol then being H n , 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