164 



PRIMARY PHOTOCHEMICAL PROCESS 



CHAP. 7 



6. Dismutation of Energy as an Alternative to a Second Primary Process 



Second Eight Quanta Theory 



As stated on page 154, an alternative to two sets of different photo- 

 chemical reactions is a single set of eight identical primary reactions, 



Photoreduction 0»ida+ion- 

 of Carbon Reduction of 



Catalyst X 

 (^Chlorophyll?) 



HXRO* 



"M h 1 



X ROH 



Photoxidation of 

 an Intermediate 

 Catalyst, ROH 



RO- 

 t 



Oxidation 

 of Woter 



► ROH 



"^ROOH' 



->^2R0H+0a 



► ROOH-' 



^->ROH 



Scheme 7.VA. — Photosynthesis according to Franck and Herzfeld. This is a varia- 

 tion of scheme 7.V, with the carbon dioxide complex {C02! and its reduction inter- 

 mediates substituted for the intermediate oxidant. The intermediate reductant is 

 designated as ROH (instead of Z). The central catalyst X (which corresponds to Y 

 in scheme 7.V) may be chlorophyll. 



coupled with secondary processes by which the energy contained in 

 eight primary intermediate products is transferred to four secondary 

 intermediates. As an example, we assume that the primary reactions 

 are all of the type (7.10a). This assumption leads to the following 

 mechanism : 



