Photolysis with krypton lamp

The vacuum ultraviolet photolysis source was a krypton resonance lamp, constructed with some modifications according to the design of workers at the National Bureau of Standards (22, 29). This lamp, fitted with lithium fluoride windows, was sealed directly to the reaction vessel whose volume was ca. 50 cc. The spectral emission of the lamp was examined with a scanning monochromator of the Seya-Namioka type. Some 75% of the emission in the region 1000-1600 A. was found to consist of the 1236-A. line. All photolysis experiments were carried out with a sample pressure of 40 mm. Hg. In addition to the 1236-A. line,... 

Table IV gives the relative product distribution from the vacuum ultraviolet photolysis of ethyl chloride at 40 mm. pressure using the 1236-A. krypton resonance line. Owing to the low intensity of emission from the resonance lamp, higher pressures were not used in the photolysis experiments in order to prevent the major portion of the reaction from occurring in the region of the window where surface interactions are likely. Therefore, to provide a basis for more direct comparison between the photolytic and radiolytic yields, the radiolysis of ethyl chloride was also examined at 40 mm. pressure. The relative yields from several experiments of the latter study are given in Table IV. The lowest conversion yields from the radiolysis at the lower pressure show a relative distribution which is in close agreement with the relative product distribution detected from the radiolysis at 357 mm. Therefore, there is no substantial pressure effect on the decomposition product yields in ethyl chloride over the range 40-357 mm.

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