202 



LIGHT AND LIFE 



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Fig. 2. Iliu)ics(eiue (|iiantuni yield of luniinol as a function of pH. 



by White, the fUioiescence quantum yield of a crystallized sample 

 of the HCl salt of amiiiophthalic acid was measured as a function 

 of pH. These data are shown in Fig. 3. Fig. 4 shows the comparison 

 between the luminol chemiluminescence emission in 0.1 A^ NaOH 

 and the fluorescence emission of aminophthalic acid, also at 0.1 N 

 NaOH. If anything, the spectra apjjear to coincide even more closely 

 than in the case of luminol shown in Fig. 1. If the oxidi/ed product 

 molecule is the light-emitting species, it would certainly simplify the 

 picture by obviating the necessity for imposing energy transfer. 



From Fig. ?> it is seen that the fluorescence quantinn yield of 

 aminophthalic acid decreases rapidly below pW 11. The luminol 

 light reaction initiated with NaOCl has been reported to show an 

 intensity maximum at pH 11 (1). Although light intensity is pri- 

 marily a measure of the rate of a reaction rather than the efficiency, 

 these facts might suggest a direct relation between the chemilumines- 

 cence quantinn yield and the fluorescence efficiency of excited amino- 



