photon exposure, \(H_{\text{p}}\)
Photon irradiance, Ep, integrated over the time of irradiation for a beam incident from all upward directions. SI unit is m-2.
  1. Mathematical definition: \(H_{\text{p}} = \int_{t}E_{\text{p}}\text{d}t\). If the @P04637-2@ is constant over the time interval, \(H_{\text{p}} = E_{\text{p}}t\).
  2. This term refers to a beam not scattered or reflected by the target or its surroundings. For a beam incident from all directions photon fluence (\(H_{\text{p,o}}\), \(F_{\text{p,o}}\)) is an equivalent term.
  3. This quantity can be used on a @C01019@ basis by dividing \(H_{\text{p}}\) by the @A00543@, the symbol then being \(H_{n\text{,p}}\), the name 'photon exposure, amount basis', SI unit is \(\text{mol m}^{-2}\); common unit is \(\text{einstein m}^{-2}\).
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 394 (