Wolff rearrangements can be induced under thermolytic, photolytic, and transition-metal-catalyzed conditions. Decomposition reactions can be generally classed into three categories; thermal, electrolytic, and photolytic decomposition reactions. The absorption at surface has two possible ways, photolytic and pyrolytic. Photolytic nitrogen splitting is also considered. Under both thermolytic and photolytic conditions, there exist competing concerted and stepwise mechanisms. The color is produced by photolytic reactions under the influence of sunlight. Photolytic producers consist of algae and certain photosynthetic bacteria. Photolytic far ultraviolet radiation is needed for both decarbonylations. Some of the abiotic pathways in the environment studied are hydrolytic reactions and photolytic reactions. Group 6 metal carbonyls upon photolytic activation catalyze dehydrogenation of AB. If intense exposure continues, such photolytic silver clusters grow to visible sizes.