Change in the rate of a chemical reaction or its @I03042@ under the action of @UT07492@, @VT07496@ or @IT07399@ radiation in the presence of a substance—the @PT07446@—that absorbs light and is involved in the chemical @T06446@ of the reaction partners.
PAC, 2007, 79, 293. (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 384 [Terms] [Paper]