703 



Walter F. Bertsch, J. B. Davidson, and J. R. Azzi 





Exponential phase cultures of Chlorella pyrenoidosa strain 252, obtained 

 from the Culture Collection of Algae, Indiana University, were used in all 

 experiments. These cultures had been grown at 1 8° C in Knop solution 

 aerated with 5%C02~95% air under continuous illumination from neon arcs. 



RESULTS 



Figure 1 shows the 1 .5 to 8 msec decay of delayed light emission from 

 unpoisoned cells. 



UNCLASSIFIED 

 ORNL-DWG 63-5645 



£ 



2 4 6 



TIME AFTER CENTER OF EXCITING FLASH (msec) 



Figure 1 . Effect of excitation intensity on delayed light 

 emission from 1.5 to 8 msec . Fast components in the 

 decay are present only after high Intensity excitation. 



The time course of decay depends on the intensity of exciting light. Since 

 the fast components of delayed light emission are present only at very high 

 intensitiesof II lumlnatlon, we have used the highest intensity shown in Figure 

 1 in our experiments. 



