104 



SPECTROSCOPIC INVESTIGATIONS 



this possibility when considering the nature of the Hght-emitting 

 molecules in bioluminescence. 



At Utrecht, Miss van der Burg (1943, 1950 a and b) examined the 

 emission spectra of a number of chemiluminescent reactions in solu- 

 tion and the fluorescence spectra of the chemiluminescent compounds. 

 In Fig. 4, the emission spectra are given of the reaction of dimethyl- 

 bisacridinium nitrate with hydrogen peroxide at three different tem- 

 peratures. Obviously, in this case there is more than one chemilumi- 

 nescent reaction, and at temperatures between 20° and 94° C, the 

 resulting emission spectra could be described as linear combinations 

 of two different spectra, I and II. The spectrum obtained at 94° C is 

 practically identical with I, and the low temperature spectrum is very 

 close to II. The general form of these two spectra makes it likely that 

 both belong to derivatives of acridine, e.g.. Fig. 3. Now it appears 

 that the high-temperature component, I, is very similar to the fluores- 

 cence spectrum of methylacridone, Fig. 5. The two spectra are not 



390 



430 



470 



510 



550 



590 



Fig. 5. A comparison of the high-temperature chemilumiiescence spectrum of di- 

 methylbisacridinium nitrate ( ) with the fluorescence spectrum of meth- 

 ylacridone ( ). 



