Product of the quantum yield by the absorption cross-section, σ Φ.
SI unit is m 2; commonly expressed in cm2.
Source:
PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 318 (https://doi.org/10.1351/pac200779030293)