Photochemical measurements at 1849 Å: ethylene as an actinometer and a method for estimating extinction coefficients

The quantum yield of formation of hydrogen from the photolysis of ethylene at 1849 A has been measured by use of nitrous oxide as an actinometer and found to be 0·62 (± 0·01). This value, of importance when using ethylene as a chemical actinometer, is substantially lower than that reported previously.To ensure that the majority of the light was absorbed by the actinometer, a method was devised which can be used to estimate extinction coefficients photochemically.