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RADIATION BIOLOGY 



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TETRAHYOROPORPHIN 





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CALC, 

 C. OF G. 



OBSERVED 

 SINGLETS 



CALC. 

 C. OF G. 



OBSERVED 

 SINGLETS 



Fig. 2-19. Comparison of calculated with observed energy states for porphin and 

 tetrahydroporphin. Calculations corrected for nitrogen electron attraction (half that 

 assumed by Longuet-Higgins et al, 1950). In "observed" columns, vibrational 

 structure is omitted for simplicity. Length of horizontal lines indicates approximate 

 intensity of transition from ground state. Double lines indicate double degeneracy. 

 Slant lines indicate unknown region. Dots indicate numerous additional calculated 

 levels. Arrow at left of porphin diagram shows relation of hypothetical ^U state to 

 'Qi in chlorophyll. 



