§10.6 Photochemistry 6.3 Photochemistry (2) The second law of photochemistry /The law of photochemical equivalence One quantum of radiation absorbed by a molecule activates one molecule in the primary step of photochemical process. E=hy≥印F u=Lhy=0.1196 vJ mol- Einstein and Stark. 1912 one einstein(2) The second law of photochemistry / The law of photochemical equivalence One quantum of radiation absorbed by a molecule activates one molecule in the primary step of photochemical process. Einstein and Stark, 1912 6.3 Photochemistry  = Lh = 0.1196  J mol-1 one einstein E = h  F-F §10. 6 Photochemistry