@O04362@ reactions induced by light. Common processes are: 1, the loss of one or more electrons from a chemical species as a result of @P04613@ of that species; 2, the reaction of a substance with oxygen under the influence of light. When oxygen remains in the product this latter process is also called @P04641@. Reactions in which neither the substrate nor the oxygen are electronically excited are sometimes called photoinitiated oxidations.