88 J. L. ROSENBERG, S. TAKASHIMA, R. LUMRY 



can react immediately with the second reactant. Electronic quanta 

 travel by induction resonance to these trapping centers where they 

 are rapidly and efficiently converted into chemical energy. The small 

 population of these centers in itself allows only a \'ery small instan- 

 taneous concentration of pigment molecules in the latter state and 

 thus explains our negative findings. 



Witt's observation (7) that the intermediate he studied Avas 

 limited by a saturation process may provide some support for the 

 latter picture; but we do not j^et know that Witt's spectral changes 

 are due to the trapping center. They may be due to some pigment, 

 perhaps one of the cytochromes as Duysens has suggested (1), well 

 removed in the reaction chain from chlorophyll and other molecules 

 immediately involved with the pick-up and conversion of excitation 

 energy into chemical energy. 



Discussion 



Frank Allen : Were your samples in complete darkness before the bright flash? 



Rosenberg : We tried complete darkness for up to a half hour and some times 

 dim light — room light — and we varied the conditions in the presence or ab- 

 sence of oxygen or the presence or absence of a supplied oxidizing agent and we 

 still could observe nothing. 



References 



1. Duysens, L. N. M., Science, 120, 353 (1954); this volume. 



2. Franck, J., Daedalus, 86, 17 (1955) ; this volume. 



3. Gaffron, H., and Wohl, K., Naturwiss., 24, 89 (1936). 



4. Linschitz, H., this volume. 



5. Livingston, R., /. Am. Chem. Soc, 77, 2179 (1955); this volume. 



6. Porter, G., Proc. Roy. Soc. (London), A200, 284 (1950). 



7. Witt, H. T., Naturwiss., 42, 72 (1955); Z. phijsik. Chem. N. S., 4, 120 (1955); 



this volume. 



8. Franck, J., and Livingston, R. S., Revs. Mod. Phys., 21, 505 (1949). 



