exposure

in photochemistry
https://doi.org/10.1351/goldbook.ET07373
Term generally applied to the time-integrated radiation incident from all upward directions on a small sphere divided by the cross-sectional area of that sphere.
Source:
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 338 [Terms] [Paper]