## photon exposure, $$H_{\text{p}}$$

https://doi.org/10.1351/goldbook.P04632
@P04637-1@, $$E_{\text{p}}$$, integrated over the time of @I03255@ for a beam incident from all upward directions. SI unit is $$\text{m}^{-2}$$.
Notes:
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 $$\text{einstein m}^{-2}$$.
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 394 [Terms] [Paper]