https://doi.org/10.1351/goldbook.DT07353
Set of rules proposed in 1975 to classify @P04585@ based on @C01348@ and under the assumption that all photochemical processes are controlled by the generation of @P04840@ with characteristics of @D01765@, i.e., considering the physical fact that the initial single excitation separates two electrons of a pair into two distinct orbitals. The reactions are classified according to their topicity, i.e., the total number and nature of available radical sites generated in the primary photochemical product.