George Porter shared half the Nobel prize in chemistry with Ronalg Norrish "for their studies of extremely fast chemical reactions, effected by disturbing the equlibrium by means of very short pulses of energy.” The other half was won by Manfred Eigen. George Porter began working on fast chemical reactions two decades before winning his Nobel Prize. At that time, the methods to study fast reactions were just beginning. His idea of flash photolysis began around 1960. In this, an extremely short and intense pulse of light (which included the ultraviolet region to assure dissociation) was used to dissociate gas molecules. A second time-delayed flash was used to observe the absorption spectrum by the free radicals and the recombining molecules. The absorption spectrum was imaged on photosensitive film. Porter and Norrish were also able to study chemical kinetics, determining rates of fast reactions with short intense flashes of light.