Organic Photochemistry,Photosynthesis,Photochemical smog event,Organic Photochemistry,Pathways of photochemical processes,Left: High power LED; Right: Photo microreactor,Essential criteria for all photochemical reactions:1.Molecule must absorb light 2.Radiation energy must match energy difference of ground and excited state,Research Method 1：Group Theory,Research Method 2：Quantum Theory,Research Method 3：Experiment,Application- Synthesis Cubane,Vitamin D2,UV,Vitamin D2,ergosterol,
