The Wolff rearrangement can be induced via thermolysis, photolysis, or transition metal catalysis. Routes of loss and degradation include runoff, volatilization, photolysis and aerobic and anaerobic biodegradation. In catalysed photolysis, light is absorbed by an adsorbed substrate. Known degradation pathways are through&colon; photolysis, chemical dissociation, sorption, bioaccumulation and plant or animal metabolism. Photosystem II obtains electrons by oxidizing water in a process called photolysis. In organic synthesis, hydroxyl radicals are most commonly generated by photolysis of 1-hydroxy-2(1"H")-pyridinethione. Transient-absorption spectroscopy (TAS), also known as flash photolysis, is an extension of absorption spectroscopy. The rapid photolysis and reformation of ozone heats the stratosphere resulting in a temperature inversion. It is prepared by photolysis of hydrogen fluoride in a solid argon matrix. Excited state absorption measurements are done using pump-probe techniques such as flash photolysis. Isolated photosystems offer the most direct connection between water photolysis and anode reduction. The enhancement of PABA photolysis by bicarbonate is due to carbonate radicals. Thionyl chloride is susceptible to photolysis, which primarily proceeds via a radical mechanism. NOM favors the indirect photolysis of PABA by absorbing the sunlight and weakening its intensity. Imidazole can be synthesized by the photolysis of 1-vinyltetrazole.